How has the biogeography of Gondwanan mammalian clades varied over deep time?

冈瓦纳哺乳动物进化枝的生物地理学如何随着时间的推移而变化？

• 批准号: 2440375
• 金额: --
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2440375
• 关键词: How; biogeography; Gondwanan; mammalian; clades

My proposed project will focus on resolving biogeographical trends in Gondwanan mammalian clades. Specifically, I will quantitatively compare the potential for marsupials and placentals to engage in intercontinental dispersal, which could explain their disjunct distributions. South America and Australasia were both adjacent to Antarctica until the Eocene, with many clades continuously dispersing between the three continents (e.g. Reguero et al. 2014, Goin et al. 2015). Thus, it is unlikely that significant physical barriers prevented marsupials and placentals from establishing a homogenous distribution across Gondwana. As such, my initial hypothesis is that mammalian dispersal across Gondwana was dictated primarily by the limitations of and interactions among ecological niches, establishing in turn a baseline from which the present-day distributions of marsupials and placentals originated. I will specifically test the following: A) I hypothesize that the dispersal of clades was facilitated by 'dispersal corridors' of more suitable habitat. To test for this, I will model the habitat suitability for marsupials and placentals in Australasia, South America and Antarctica during the Mesozoic and Cenozoic. B) I hypothesize that clades with greater niche breadths were those that could have dispersed more successfully between continents, and indeed those more capable of dispersing in the present-day. Consequently, I will examine how niche breadths of placentals and marsupial groups differ in Australasia, South America and Antarctica (e.g. Garcia-Navas and Rodriguez-Rey 2019). C) I hypothesize that Australasian marsupials have filled the entire range of niches occupied by placentals elsewhere. I plan to test for this, perhaps demonstrating in the process the extent to which marsupials have been ecologically excluded in South America and elsewhere. D) Finally, I hypothesize that marsupials generally show greater niche conservatism - a tendency for a clade to retain a consistent ecological niche (e.g. Crisp and Cook 2012) - explaining at least some limitations to their diversity and biogeography. Thus, I will compare niche conservatism in marsupials and placental clades.

我提议的项目将侧重于解决冈瓦纳哺乳动物进化枝的生物地理趋势。具体来说，我将定量比较有袋动物和胎盘动物进行洲际扩散的潜力，这可以解释它们的不连续分布。直到始新世，南美洲和澳大拉西亚都与南极洲相邻，许多分支不断分散在这三个大陆之间（例如Reguero等人，2014年，Goin等人，2015年）。因此，重大的物理障碍不太可能阻止有袋动物和胎盘动物在冈瓦纳大陆建立同质分布。因此，我最初的假设是，哺乳动物在冈瓦纳大陆的扩散主要是由生态位的限制和相互作用决定的，从而建立了当今有袋动物和胎盘动物分布的基线。我将具体测试以下内容：A）我假设更合适栖息地的“扩散走廊”促进了进化枝的扩散。为了测试这一点，我将模拟中生代和新生代期间澳大利亚、南美洲和南极洲有袋动物和胎盘动物的栖息地适宜性。 B）我假设生态位宽度更大的进化枝能够在各大洲之间更成功地分散，而且实际上是那些在当今更有能力分散的进化枝。因此，我将研究澳大利亚、南美洲和南极洲胎盘动物和有袋动物群体的生态位宽度有何不同（例如 Garcia-Navas 和 Rodriguez-Rey 2019）。 C) 我假设澳大利亚有袋动物已经填补了其他地方胎盘动物所占据的整个生态位。我计划对此进行测试，或许可以在这个过程中展示有袋动物在南美洲和其他地方被生态排斥的程度。 D）最后，我假设有袋动物通常表现出更大的生态位保守性 - 一个进化枝保留一致的生态位的趋势（例如 Crisp 和 Cook 2012） - 至少解释了它们的多样性和生物地理学的一些限制。因此，我将比较有袋动物和胎盘进化枝的利基保守性。