Collaborative Research: Origins and drivers of extinction of Caribbean avifauna

目前的脊椎动物多样性已经被大约18,000年前最后一个冰河时代结束后开始的持续大规模灭绝事件所戏剧性地塑造。至少有一些迁徙的时间往往与人类抵达新殖民地的时间相吻合。虽然自上一个冰河时代以来，全球范围内都发生了干旱，但构成加勒比海的岛屿可能是受灾最严重的地区。这个岛屿系统拥有丰富的保存完好的古生物和考古遗址，保存了过去鸟类多样性和人类居住的壮观记录。尽管如此，我们对加勒比鸟类群落长期变化的模式、原因和后果的了解仍然令人惊讶地有限。这种知识差距阻碍了我们对过去多样性变化及其原因的理解，从而阻碍了我们管理和保护未来剩余多样性的能力。这项研究的重点是利用化石中的DNA（古代DNA）来了解灭绝物种的分类学亲缘关系，并通过放射性碳测年来确定物种的最后一次出现，从而缩小这些知识差距。这种方法提供了关键信息，以确定这些物种是谁，并确定它们与气候变化和人类到达岛屿的浪潮有关的损失时间。该项目还侧重于使它们更容易灭绝的物种的特征（例如，不会飞），以更全面地了解过去灭绝的原因，并预测现有物种的灭绝风险。该项目通过其教育和外联部分产生了广泛的社会影响。该项目将为代表性不足的学生提供科学培训，重点是灭绝和古代DNA，并与佛罗里达汤姆森地球科学研究所（TESI）的科学家在每个佛罗里达学校（SEFS）计划合作，为佛罗里达的K-12课程开发课堂内容。为了增进公众对科学的理解，并加强对受威胁的加勒比鸟类的保护工作，研究人员将制作一部英语和西班牙语的纪录片，并与博物馆的外展工作合作，向加勒比岛屿的广大观众宣传。据估计，自更新世晚期以来，加勒比地区12%的鸟类物种要么灭绝，要么灭绝。其中许多现在被认为濒临灭绝或受到威胁。人们对人类在这些灭绝和人口损失中所扮演的角色知之甚少。由于人类到达这些岛屿的时间比大陆晚得多，考古学和古生物学证据可以用来确定人类如何在到达后与当地动物群相互作用，以驯化，转移并导致某些物种的灭绝。这种鸟类多样性消失的证据是零碎的，往往只有少数标本与有限的形态特征。这对正确的系统发育位置造成了挑战，特别是考虑到由于共同的生活史（如不会飞）而产生的趋同潜力。在这个项目中，研究人员将建立包括现代，灭绝和灭绝分类群的鸟类分支的系统发育树，以确定这些物种的系统发育和性状亲和力。这项工作还将阐明加勒比地区全部特有动物的地理分布模式，这种模式由于神秘的分类群的排除而被掩盖，并从系统发育和特征多样性的角度描绘生物多样性丧失的程度。下一步的关键是将新的系统发育知识整合到更大的整体鸟类多样性模式的背景下，明确量化过去的系统发育多样性在整个加勒比地区的损失。我们将产生一个新的度量标准，多样性损失风险，它整合了对物种遗传学，特征和过去灭绝事件的洞察力，以揭示哪些现存物种对防止永久性系统发育多样性损失最为关注。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Current vertebrate diversity has been dramatically shaped by an ongoing mass extinction event that began after the last ice age ended, approximately 18,000 years ago. The timing of at least some of these extinctions often coincides with human arrival into newly colonized areas. While extinctions since the last ice age have occurred worldwide, the islands that make up the Caribbean have been perhaps the single hardest hit region. This island system, rich in well-preserved paleontological and archaeological sites, has preserved a spectacular record of both past bird diversity and human occupation. Still, our knowledge of the patterns, causes, and consequences of long-term changes to Caribbean bird communities remains surprisingly limited. This knowledge gap hampers our understanding of past diversity changes and its causes, and thus our ability to manage and conserve remaining diversity into the future. This research focuses on closing these knowledge gaps using DNA from fossils (ancient DNA) to understand taxonomic affinities of extinct species, and radiocarbon dating to determine the last occurrence of a species. This approach provides critical information to determine who these species were, and to time their losses in relation to climate change and waves of human arrivals to the islands. This project also focuses on the characteristics of species that have made them more vulnerable to extinction (for example, flightlessness) as a means to more completely understand the causes of extinction in the past and forecast the extinction risk for existing species. This project has broad societal impact through its educational and outreach components. The project will provide training for underrepresented students in science, focusing on extinction and ancient DNA, and develop classroom content for K-12 classes in Florida in partnership with the University of Florida Thomson Earth Science Institute’s (TESI) Scientist in Every Florida School (SEFS) program. And to further public understanding of science, and to bolster conservation efforts for threatened Caribbean birds, the researchers will develop a documentary video in both English and Spanish and work with museum-based outreach efforts to inform wide audiences across the Caribbean islands.It is estimated that 12% of the bird species in the Caribbean either went extinct or were extirpated since the late Pleistocene, with many more now considered to be endangered or threatened. Less well understood is the role humans have played in these extinctions and population losses. Because human arrival to these islands occurred much later than on the mainland, archeological and paleontological evidence can be used to determine how humans interacted with the local fauna upon their arrival to domesticate, translocate, and cause the extinction of some species. Evidence of this lost avian diversity is fragmentary, often represented by only a few specimens with limited morphological characters. This causes challenges for proper phylogenetic placement, especially given potential for convergence due to shared life histories such as flightlessness. In this project researchers will build phylogenetic trees of clades of birds including modern, extinct and extirpated taxa to determine the phylogenetic and trait affinities of these species. This work will also elucidate biogeographic patterns of the full endemic fauna of the Caribbean, that has been obscured due to extinctions of enigmatic taxa, and build a picture of the level of biodiversity loss in terms of phylogenetic and trait diversity. A key next step is to then integrate new phylogenetic knowledge into a larger context of overall avian diversity patterns to explicitly quantify past loss of phylogenetic diversity across the Caribbean. We will generate a new metric, diversity loss risk, that integrates insight from phylogenetics, traits, and past extinction events to reveal which extant species are of greatest concern for preventing permanent phylogenetic diversity loss.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.