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Impact of Perception on Animal Conservation Efforts and Biodiversity
By Adyasha Padhi, Biochemistry and Molecular Biology and Sociocultural Anthropology ’25
Humanity has impacted our planet’s biodiversity in extensive ways, both deliberately and accidentally. According to the World Wildlife Fund, there has been an average of a 69% decline in worldwide biodiversity since 1970 [1]. However, some geographical areas and ecosystems are disproportionally affected. Biodiversity in the Caribbean and Latin America has dropped 94% and their freshwater populations are experiencing an 83% decrease in biodiversity [1]. The four most significant drivers of biodiversity loss are land use change (30%), overexploitation (20%), climate change (14%), and invasive species (11%), all of which are associated with human activity [2]. Overall, the impact of all biodiversity drivers is increasing and so is the rate of biodiversity decline.
One of the major ways that we attempt to repair the damage that we have done to our planet is through wildlife conservation efforts. However, examining conservation efforts reveals startling trends in which species receive focused protection, policy efforts, research, and funding. These inequities call into question the efficacy of many widespread conservation programs.
What is biodiversity and why is it important:
Biodiversity refers to the variety of life on Earth at all levels, from genetic diversity in a population to organism diversity within an ecosystem. This encompasses both the sum of total life forms across an area and the range of differences between those forms. While the biodiversity of some organisms is widely valued instinctively, some are not, such as microbiota, insects, and plants. Nevertheless, these undervalued organisms perform functions that are essential to maintaining stable ecosystems. Biodiversity supports healthy life on Earth– a lack of diversity at any level of life can lead to ecosystem collapse. This is because greater biodiversity in individuals, species, and ecosystems leads to greater ecosystem stability, and the populations within them are more likely to be able to withstand a range of disturbances, such as disease outbreaks and climate change.
Biodiversity is usually explored at three levels: genetic, species, and ecosystem. For the purposes of conservation, species diversity is most often the focus. While genetic and ecosystem diversity are both extremely important, species diversity can offer insight into the health of both of these while being more manageable in scope. If species diversity is low in an ecosystem, that has implications on both the genetic diversity of the species that make up that ecosystem and that ecosystem as a whole in relation to other ecosystems. One way to measure species biodiversity is with a biodiversity index. A simple biodiversity index is calculated by dividing species richness (the number of species in an area) by species evenness (the total number of individuals in the same area) [7].
By using metrics such as the biodiversity index, researchers have found that biodiversity has been decreasing at an unprecedented rate [3]. Furthermore, certain areas around the equator known as biodiversity hotspots are experiencing biodiversity loss at even higher rates than other areas [3]. Human activity is contributing to all of the major driving factors for biodiversity decline, such as climate change, the effects of which are accelerated by the continued loss of biodiversity in ecosystems worldwide, creating a cycle of damage and loss.
Conservation: Who gets chosen, and why?
One way to mitigate the negative impacts humans have had on the planet is through conservation efforts, or protecting species and their habitats to restore populations and ecosystems. Conservation efforts typically fall into one of two categories: preventing further destructive forces from acting on ecosystems, such as stopping deforestation or stimulating populations through breeding and protection, in order to revitalize injured populations. These efforts are typically in-situ (conservation of habitats, species, and ecosystems where they naturally occur) or ex-situ (conservation of elements of biodiversity out of the context of their natural habitats, such as zoos, seed banks, and botanical gardens).
Financial, land, and labor resources are limited, so the conservation of certain areas or species is forced to be prioritized over others. A common approach for selecting these priority areas for conservation is to focus on hotspots of diversity. These “hotspots” are regions of high conservation priority due to their high levels of richness in species, rates of endemism (uniqueness to that certain region), and threats to survival. Currently, there are 36 designated hotspots worldwide. These biogeographic regions are most commonly found around the equator and hotspots have lost around 85% of their habitat area [3].
Another metric used to determine the status of certain species is the International Union for Conservation of Nature (IUCN) Red List. The IUCN is an international organization for nature conservation and the sustainable use of natural resources. It is most well known for its Red List, which is regarded as the world’s most comprehensive inventory of the global conservation status of biological species. They report that they have assessed 42,100 species at risk of extinction, but a 2019 United Nations report estimates that of all existing species, a million are at risk of extinction in total. This disparity reflects how few existing species have been assessed by the IUCN. Prioritizing certain species and ecosystems is needed due to the limited resources that conservation organizations have, and the increasingly complex social, cultural, and political factors that further inhibit conservation efforts.
Conservation efforts are often focused on a single species, and these species are often categorized into three categories that define their relation to their ecosystem: keystone, indicator, or flagship, with overlap between the categories. Keystone species play an essential role in the structure, function, or productivity of a habitat or ecosystem and the disappearance or diminishment of one of these species may lead to significant ecosystem change and dysfunction. One famous example of a keystone species is the Grey wolf in Yellowstone. As predators that regulate prey populations, the wolves enabled many species of plants and animals to flourish. After their disappearance in 1926, their reintroduction into Yellowstone in 1995 was a conservation effort that had highly successful effects on the entire food structure that defines the Northern Rockies ecosystem [12]. An example of a keystone species acting as ecosystem engineers are beavers, who regulate tree growth in the river ecosystems and also divert rivers with their dams, creating wetlands and ponds which support a wide range of organisms, which would not be able to survive in the more aggressive environment of a river. Despite their small size, bees are also a keystone species due to their integral role in pollination [13]. Plants too can be keystone species, such as Mangrove trees, which play an essential role in many coastal ecosystems by protecting coastlines from the impacts of waves and reducing erosion, while also providing a safe haven for small marine organisms to survive, which in turn has wider impacts throughout the food web.
Indicator species are species or groups of species chosen as an indicator or proxy for the state of an ecosystem. An example of this is crayfish as indicators of freshwater quality and peregrine falcons as an indicator of pesticide loads. Flagship species are selected to act as a symbol for a defined habitat or environmental cause due to their “charismatic” nature, especially in Western cultures, which is often where the funding for many conservation campaigns comes from [5]. These flagship species are typically large mammals that may or may not be keystone species and are not necessarily good indicators of biological processes in their ecosystems or of the conversation status of their ecosystem. Examples include tigers, kangaroos, elephants, and pandas [11].
Flagship species campaigns centered around these “charismatic” animals have been found to be more effective than other types of conservation campaigns [4]. Researchers have found that public donors were more likely to donate to a flagship charismatic species, regardless of the endangered status of the species [4]. Features of charismatic species include colorful coats or forward-facing eyes [6] because these appeal most to the broadest audience and these species are often featured in media & spaces where the public can interact with them, such as in movies or in zoos. The Similar Principle Theory finds that humans have a preference for animal species that are more similar to them. This is in both physical characteristics, such as forward-facing eyes and expressive faces, and social characteristics. As such, some researchers posit that the chances of survival for many species depend as much on human preferences as on existing biotic and abiotic factors, if not more [4].
Paradoxically, many of the animals regarded as the most charismatic are at high risk of imminent extinction, which some researchers attribute to the biased perception of the abundance of these animals since they are commonly overrepresented in our culture, such as pandas, tigers, and lions being common in our zoos, media, and educational material [6]. While some have called out this focus on animal charisma as being too narrow and excluding many species, charismatic flagship species conservation campaigns have been more successful in securing funding than campaigns that do not feature a flagship species [4]. However the status of many other species which share their habitat – or are vulnerable to the same threats – may also be improved by campaigns that target charismatic species. This is due in part to the large habitats that charismatic animals tend to live in due to their size and their position often being higher up on the food chain. Ultimately, researchers are calling for the shift away from campaigns centered around charismatic species and towards ones that focus more on the health of the ecosystem as a whole, even if this is less visible [6].
Conclusion
Biodiversity on all levels is an essential aspect of global health as it supports ecosystem health and stability via pollination, water purification, climate regulation, seed dispersal, agricultural pest control, and nutrient cycling. As such, all organisms, biotic, and abiotic factors that make up an ecosystem are extremely important in their own ways, and this means that even organisms that we don’t intrinsically value or find charismatic are important. Protecting all species is integral to protecting the health of the world as a whole and combating climate change.
References
[1] “69% average decline in wildlife populations since 1970, says new WWF report,” World Wildlife Fund, 2022. https://www.worldwildlife.org/press-releases/69-average-decline-in-wildlife-populations-since-1970-says-new-wwf-report
[2] The Royal Society, “What is the human impact on biodiversity? | Royal Society,” royalsociety.org, 2022. https://royalsociety.org/topics-policy/projects/biodiversity/human-impact-on-biodiversity
[3]N. Myers, R. A. Mittermeier, C. G. Mittermeier, G. A. B. da Fonseca, and J. Kent, “Biodiversity hotspots for conservation priorities,” Nature, vol. 403, no. 6772, pp. 853–858, Feb. 2000, doi: https://doi.org/10.1038/35002501.
[4]A. Colléony, S. Clayton, D. Couvet, M. Saint Jalme, and A.-C. Prévot, “Human preferences for species conservation: Animal charisma trumps endangered status,” Biological Conservation, vol. 206, pp. 263–269, Feb. 2017, doi: https://doi.org/10.1016/j.biocon.2016.11.035.
[5]C. Mazzoldi et al., “From sea monsters to charismatic megafauna: Changes in perception and use of large marine animals,” PLOS ONE, vol. 14, no. 12, p. e0226810, Dec. 2019, doi: https://doi.org/10.1371/journal.pone.0226810.
[6]F. Courchamp, I. Jaric, C. Albert, Y. Meinard, W. J. Ripple, and G. Chapron, “The paradoxical extinction of the most charismatic animals,” PLOS Biology, vol. 16, no. 4, p. e2003997, Apr. 2018, doi: https://doi.org/10.1371/journal.pbio.2003997.
[7]“Guide on biodiversity measurement approaches (2nd edition),” Finance for Biodiversity Pledge. 2022. https://www.financeforbiodiversity.org/publications/guide-on-biodiversity-measurement-approaches/
[8]K. Whiting, “6 charts that show the state of biodiversity and nature loss – and how we can go nature positive,” World Economic Forum, Oct. 17, 2022. https://www.weforum.org/agenda/2022/10/nature-loss-biodiversity-wwf/
[9]J. H. Lawton and K. J. Gaston, “Indicator Species,” ScienceDirect, Jan. 01, 2001. https://reader.elsevier.com/reader/sd/pii/B9780123847195000745?token=68CA7F85D7A3FD42B151DC0DDD681D1E44822EC03A422ABFA252CF19E4E9E70F88BD7C79CB9E562C1AD10E92193926FA&originRegion=us-east-1&originCreation=20230411171712
[10]M. C. Horner-Devine, K. M. Carney, and B. J. M. Bohannan, “An ecological perspective on bacterial biodiversity,” Proceedings of the Royal Society of London. Series B: Biological Sciences, vol. 271, no. 1535, pp. 113–122, Jan. 2004, doi: https://doi.org/10.1098/rspb.2003.2549.
[11]J. Qian and H. Zhuang, “Selecting flagship species to solve a biodiversity conservation conundrum,” Plant Diversity, Jan. 2021, doi: https://doi.org/10.1016/j.pld.2021.01.004.
[12]A. P. Dobson, “Yellowstone Wolves and the Forces That Structure Natural Systems,” PLoS Biology, vol. 12, no. 12, p. e1002025, Dec. 2014, doi: https://doi.org/10.1371/journal.pbio.1002025.
[13]A. Easton-Calabria, K. C. Demary, and N. J. Oner, “Beyond Pollination: Honey Bees (Apis mellifera) as Zootherapy Keystone Species,” Frontiers in Ecology and Evolution, vol. 6, Feb. 2019, doi: https://doi.org/10.3389/fevo.2018.00161.
Gene editing invasive species out of New Zealand
By Jessie Lau, Biochemistry and Molecular Biology ‘20
Authors Note: Since the advent of Clustered Regularly Interspaced Short Palindromic Repeats-CRISPR Associated Protein 9 (CRISPR/Cas9) discovery and biotechnological breakthroughs thereafter, this revolutionary application has been primarily focused on human health, particularly fostering solutions to numerous debilitating ailments. However, the general public has offered little attention towards the use of this engineering feat in a broader ecological system. Upon watching the new Netflix original Unnatural Selection, discussion of considering the use of CRISPR/Cas9 in New Zealand’s effort to completely eradicate invasive species piqued my interest. The following article is an exploration of CRISPR/Cas9 prospect into New Zealand’s bold environmental pursuit and its potential ecological impact.
Abstract
Since it has become feasible to cross oceans to reach unforeseeable land masses, invasive alien species (IAS) are an increasing threat to international biodiversity. Moreover, no other region faces as great of a peril as New Zealand (NZ), which holds the record as the nation with the highest survival rate of threatened avifauna (birds of a particular region) species [5]. In 2012, New Zealand physicist Sir Paul Callaghan introduced a large-scale eradication program to permanently remove eight invasive mammalian predators (rodents: Rattus rattus, Rattus norvegicus, Rattus exulans, Mus musculus; mustelids: Mustela furo, Mustela erminea, Mustela nivalis; and the common brushtail possum: Trichosurus vulpecula) [5]. Four years after this grand proposal, the NZ government committed to a national challenge titled “Predator Free 2050” (PF 2050) to pursue this audacious goal.
Introduction
Approximately 85 million years ago, NZ was one of the first landmasses to split from the supercontinent Gondwana and as it shifted away, it did not carry mammals until bats flew and aquatic species swam to this island. [7]. With the introduction of rodent species initially through Polynesian settlement some 750 years ago and thereafter European seafaring ventures, the endemic species of NZ have been left vulnerable to novel predators. Consequently, at least 51 native bird species that have evolved adaptive skills of remaining close to the ground have been unsuccessful at surviving alongside these rodent predator species [4]. These invasive omnivorous rodents prey on birds, eggs, seeds, snails, lizards, and fruits. As a result, their varied diets prompt competition with the native fauna, further placing pressure on their vulnerable survival [7]. Despite CRISPR/Cas9 modifications offering the greatest potential in gene drive to eliminate these unwanted predators, several techniques implemented to control these invasive populations, such as pesticides, trapping innovations, and biological factors have given favorable results.
Past Successes and Future Endeavors
For decades, the NZ government has pursued eradication initiatives to permanently eliminate foreign invasive species on small local islands. Through concerted efforts, several of these projects have proven successful in the restoration of the natural biodiversity this island nation boasts.
In June of 2009, the NZ Department of Conservation (DOC) undertook a multi-action plan to simultaneously eradicate rodent, rabbit, stout, hedgehog, and cat species in Rangitoto and Motutapu islands. After three years of aerial dispersion of anticoagulant Pestoff 20RTM combined with trapping and indicator dogs, the island witnessed total elimination of the islands’ stoats and four rodent species; declination of rabbit and hedgehog population by 96%; and over 50% reduction in cats [7].
Despite these successful feats, the invasive species fecundity and ability to adapt to these challenges still present an overwhelming challenge to reach the goal of complete eradication. Recently, more direct approaches delving into novel genetic inheritance techniques have been explored to serve as a potential permanent solution. Termed the“Trojan Female Technique” (TFT), the method makes use of the correlation of sperm fitness dependence on the abundance of mitochondrial DNA (mtDNA) [2]. Healthy sperm is dependent on sufficient mitochondrial level for energy production to manage motility and fertilization. For example, experiments conducted on Drosophila melanogaster supports the causation of reduced spermatogenesis and sperm maturation due to induced mutations in cytochrome mitochondrial gene [9]. Contrasting female eggs, the asymmetric greater dependence of sperm on mtDNA for normal functionality results in only male populations to be the sole source of target. Induction of mitochondrial mutations in females to compromise total sperm viability in future male progenies will serve as an effective control to population growth.
Although seemingly promising, TFT is not guaranteed to completely eradicate propagation for several reasons. For starters, males with impaired fertility can still provide sufficient sperm count to fertilize eggs on a population-based scale. Furthermore, in circumstances where females do receive nonviable sperm count, they can still seek adequate functioning sperm through matings with other males. On a larger scale, should the mutation pervade, selection pressures could still inadvertently choose for nuclear modifications to make up for the mitochondrial defects [2]. These flaws raise the need for more pervasive and permanent resolutions.
Daisy Chain CRISPR Gene Drive
The recent biochemical breakthrough underpinning the ability to effectively and precisely modify genes with CRISPR/Cas9 has allowed for potential biotechnology to boom in the realm of ecology. The simple generation of a short RNA sequence into a virus or bacterium to serve as a vector, guides the cutting mechanism of Cas9 to specific regions in the genome to be excised, prompting for these double stranded breaks to be fixed through DNA repair mechanisms. While these fixtures can potentially repair the gene, it can also raise the possibility for the gene to be disabled, introduce a new function, or create an unforeseen mutation. Given the right specific targeting in the germ line, this approach houses the innovation for exterminating entire species through gene drive [6].
The mechanism behind gene drive overthrows the traditional Mendelian sexual reproduction concept of proportional contribution from both the male and female parent. The power comes from the ability of one genetically modified (GM) contributor encoding for the ‘gene drive’ to cut the other set of chromosomes lacking these genes and replace this excision with a self-replicating copy. In effect, this divisive modification would push for an otherwise heterozygous offspring from a wild-type mating with a GM partner to become homozygous for certain genes to be carried on and propagated by future generations. Given that these genetic alterations do not affect the fitness of the organism, dissemination of 1% of the population with CRISPR modified genes can lead to 99% of the local population carrying the genetic indicator in as little as nine generations (The use of gene editing to create gene drives for pest control in New Zealand).
Such a unilateral approach poses political and ethical challenges amongst neighboring nations with diverging ecological approaches to confront pest control. Should this pervasive gene drive program reach beyond its intended border, great difficulty would arise in maintaining this ecological enclosure. For example, possum is on the list of invasive species in NZ while just 2,500 miles west, its neighbor Australia keeps this species of marsupials under protection. As such, scientists have devised a simple model to localize gene alterations, coined The Daisy Chain.
Unlike the original gene drive method in which all components necessary for transformation (CRISPR, edited DNA, and guide RNAs) are provided on the same chromosome, Daisy Chain provides a self-exhaustive means of guaranteeing genetic edits. This tool is designed so that each component required for genetic alteration is dependent on the presence of a different element upstream on the gene found on the same locus to be activated [8]. The most downstream portion of this chain contains the “load” of engineered dominant lethal genes preventing reproduction, which will be promoted to higher frequency in the population within several generations. For instance, should an engineered allele contain three elements A, B, and C, element C would render element B to drive, which will in turn cause element A carrying the final load to drive. The initial element (C in this case) does not actually drive, thus is restricted by the number of altered individuals released into the wild and will be lost via natural selection over time. During initial implementation, the presence of C will increase B in abundance, but B will eventually decline and finally disappear as C is lost in the population. The rapid rise in abundance of B will also cause A to increase in frequency within the local population; however, with the decrease of B, A would not be driven and will ultimately vanish as well [1]. Using MIT Professor Esvelt’s analogy, “… the elements of a daisy drive system are similar to booster stages of a genetic rocket: those at the bottom of the base of the daisy-chain help life the payload until they run out of fuel and are successively lost.”
Challenges with Daisy Chain CRISPR Gene Drive
CRISPR/Cas9 technology’s ability to potentially alter these invasive species’ fecundity provides an avenue of pursuing NZ’s goal of PF 2050. Despite the developed understanding of how to carry out this plan, scientists in NZ are still working to piece together the genomes of stoats and possums in order to understand where to properly facilitate the engineered RNA sequence. Other barriers that must be acknowledged are the unprecedented approach to genetically modify marsupials and the difficulty of implanting hundreds to thousands of oocytes to be dispersed amongst their population.
Beyond these known difficulties, scientists still tread in unknown terrains pertaining to whether these mutations can have pernicious effects in the survival, health, and reproductive success in propagating these mutations within their populations. Further exploration into the development of these modifications, and the potential impacts they can have on these animals, must be investigated on model organisms prior to widespread use.
Of the eight listed mammalian species vied to be permanently eradicated from NZ, Mus musculus holds the most promise, given the extensive knowledge of the Mus musculus genome. With the help of scientists outside of New Zealand, joining in on the efforts to identify which germline gene to focus on, this project has received international attention.
Although the daisy drive provides promising potential, research collaborators at MIT and Harvard have identified a possible risk of, “… DNA encoding a drive component from one element to another, thereby creating a ‘daisy necklace’ capable of a global drive” [1]. Due to this rare recombinatory event arising from the similarity of DNA sequences, these investigators have looked into circumventing the problem by creating numerous alternatives to CRISPR components and selecting the model with the greatest diversity.
Conclusion
From their renowned aviary to reptilian species, New Zealand’s islandic geographical region houses some of the most biodiverse fauna known to man. The arrival of human settlement has introduced predatory species, causing endemic species to experience extinction at concerning rates [4]. With the purpose of preserving their unique remaining diversity, New Zealand has committed to concerted efforts of varying methods to eradicate these invasive vertebrate pests. Investigation into genetic modifications can provide for more expansive and thorough techniques to eliminate these human introduced pests and allow for these endangered species to thrive once again. By further exploring daisy chain CRISPR/Cas9, this effort can be genetically inherited by offspring, allowing for nature to carry out this effort. As opposed to continued efforts of targeting each individual one by one, conservation ecologists can borrow from molecular biologist’s toolkit to revolutionize the means of pursuing pest control and perhaps even pave the road for future endeavors with similar pursuits.
References
- Esvelt, Kevin M. “Daisy Drives.” Sculpting Evolution, www.sculptingevolution.org/daisydrives.
- Gemmell, Neil J., et al. “The Trojan Female Technique: a Novel, Effective and Humane Approach for Pest Population Control.” Proceedings of the Royal Society B: Biological Sciences, vol. 280, no. 1773, 2013, pp. 1–6., doi:10.1098/rspb.2013.2549.
- Griffiths, Richard, et al. “Successful Eradication of Invasive Vertebrates on Rangitoto and Motutapu Islands, New Zealand.” Biological Invasions, vol. 17, no. 5, 2014, pp. 1355–1369., doi:10.1007/s10530-014-0798-7.
- Owens, Brian. “The Big Cull: Can New Zealand Pull off an Audacious Plan to Get Rid of Invasive Predators by 2050?” Nature, vol. 541, 12 Jan. 2017, pp. 148–150.
- Russell, James C., John G. Innes, Philip H. Brown, and Andrea E. Byrom. “Predator-Free New Zealand: Conservation Country.” BioScience 65, no. 5 (October 2015): 520–25. https://doi.org/10.1093/biosci/biv012.
- Saey, Tina Hesman. “Explainer: How CRISPR Works.” Science News for Students, 4 Dec. 2017, www.sciencenewsforstudents.org/article/explainer-how-crispr-works.
- “Why Predator Free 2050?” Department of Conservation. Accessed November 18, 2019. http://www.doc.govt.nz/nature/pests-and-threats/predator-free-2050/why-predator-free-2050/.
- Dearden, Peter K., et al. “The Potential for the Use of Gene Drives for Pest Control in New Zealand: a Perspective.” Journal of the Royal Society of New Zealand, vol. 48, no. 4, 2017, pp. 225–244., doi:10.1080/03036758.2017.1385030.
- Wolff, Jonci N., et al. “Mitonuclear Interactions, MtDNA-Mediated Thermal Plasticity and Implications for the Trojan Female Technique for Pest Control.” Scientific Reports, vol. 6, no. 1, 2016, doi:10.1038/srep30016.
- Min, John, Jason Olejarz, Joanna Buchthal, Alejandro Chavez, Andrea L. Smidler, Erika A. DeBenedictis, George M. Church, Martin A. Nowak, Kevin M. Esvelt, and Charleston Noble. “Daisy-Chain Gene Drives for the Alteration of Local Populations.” PNAS. National Academy of Sciences, April 23, 2019. https://www.pnas.org/content/116/17/8275.
“No Ecosystem is an Island”
By Daniel Friedman, Genetics ’14
For years, ecologists have modeled the biodiversity of natural forests as if they were oceanic islands, adrift in an unlivable sea of humanity. However, research published in April in Nature by C. Mendenhall et al. suggest that this is not the most accurate or predictive way to think about these pockets of nature. By comparing bat diversity on countrysides and oceanic islands, they find that fragmented land ecosystems behave markedly different than their oceanic counterparts. They find that forest “islands” maintain species at higher overall levels of biodiversity than ocean islands, and also gain/lose species in unique patterns. This has relevance to humanity’s actions to support biodiversity on land, and suggests the need for new models, metrics, and strategies of conservation.
Mendenhall, C., Karp, D., Meyer, C., Hadly, E., Daily, G., “Predicting biodiversity change and averting collapse in agricultural landscapes”, Nature, 2014.
Image from Abu Shawka, 2009. Creative Commons.