Macroecological consequences of biotic and abiotic factors in marine ecosystems through time

Thesis

This dissertation statistically investigated putative biotic and abiotic drivers of ecological characteristics over the spatial scale of ocean basins and temporal scale of millennia to millions of years. For three fundamental hypotheses in evolutionary ecology, I compared patterns of natural experiments from the fossil record against expectations from theory. The first empirical study appraised the hypothesis that competition restricts geographic distributions at the species level, and thus taxa are more widespread when in the presence of fewer competitors, such as after mass extinction events. Contrary to the prediction of competitive exclusion, brachiopod and bivalve distributions were invariant to inferred biotic pressure, while habitat type and lineage age had detectable effects on range expansion or contraction on the scale of geologic stages across the Phanerozoic. The second study estimated the degree to which plankton modulate thermal preferences vs. migrate in response to glacial–interglacial climate fluctuations. Species conserved abiotic niches over the Middle–Late Pleistocene study interval, suggesting marine species will track preferred environments rather than adapt to Anthropogenic climate warming. The final study explored relative niche change within lineages vs. across an evolutionary tree of macroperforate planktonic foraminifera. The stark stasis observed within lineages could suggest niches evolve primarily during speciation, but any signal of such punctuated equilibrium was undetectable statistically with the small phylogenetic tree and large variance within and between species. Together, these results add perspective to longstanding debates about the scaling of population- to species-level ecology and micro- to macro-evolution.

Authors: Antell, G

• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: species distributions; fossil record; planktonic foraminifera; spatial sampling standardization; ecological release; Antell GT; Gawain Antell
• Subjects: Brachiopoda; Ecology; Paleontology--Phanerozoic; Punctuated equilibrium (Evolution); Mass extinctions; Paleoceanography; Niche (Ecology); Evolution (Biology); Competition (Biology); Marine biodiversity; Adaptive radiation (Evolution); Bivalves, Fossil; Paleontology; Habitat partitioning (Ecology); Biogeography; Foraminifera, Fossil--Geographical distribution; Food chains (Ecology)