Extinction risk controlled by interaction of long-term and short-term climate change

Marine species and assemblage change foreshadowed by their thermal bias over Early Jurassic warming

A mismatch of species' thermal preferences to their environment may indicate how they will respond to future climate change. Averaging this mismatch across species may forewarn that some assemblages will undergo greater reorganization, extirpation, and possibly extinction, than others. Here, we examine how regional warming determines species occupancy and assemblage composition of marine bivalves, brachiopods, and gastropods over one-million-year time steps during the Early Jurassic. Thermal bias, the difference between modelled regional temperatures and species' long-term thermal optima, predicts a gradient of species occupancy response to warming. Species that become extirpated or extinct tend to have cooler temperature preferences than immigrating species, while regionally persisting species fell midway. Larger regional changes in summer seawater temperatures (up to +10 °C) strengthen the relationship between species thermal bias and the response gradient, which is also stronger for brachiopods than for bivalves, while the relationship collapses during severe seawater deoxygenation. At +3 °C regional seawater warming, around 5 % of pre-existing benthic species in a regional assemblage are extirpated, and immigrating species comprise around one-fourth of the new assemblage. Our results validate thermal bias as an indicator of immigration, persistence, extirpation, and extinction of marine benthic species and assemblages under modern-like magnitudes of climate change.

Cenozoic history of the tropical marine biodiversity hotspot

The region with the highest marine biodiversity on our planet is known as the Coral Triangle or Indo-Australian Archipelago (IAA)1,2. Its enormous biodiversity has long attracted the interest of biologists; however, the detailed evolutionary history of the IAA biodiversity hotspot remains poorly understood3. Here we present a high-resolution reconstruction of the Cenozoic diversity history of the IAA by inferring speciation-extinction dynamics using a comprehensive fossil dataset. We found that the IAA has exhibited a unidirectional diversification trend since about 25 million years ago, following a roughly logistic increase until a diversity plateau beginning about 2.6 million years ago. The growth of diversity was primarily controlled by diversity dependency and habitat size, and also facilitated by the alleviation of thermal stress after 13.9 million years ago. Distinct net diversification peaks were recorded at about 25, 20, 16, 12 and 5 million years ago, which were probably related to major tectonic events in addition to climate transitions. Key biogeographic processes had far-reaching effects on the IAA diversity as shown by the long-term waning of the Tethyan descendants versus the waxing of cosmopolitan and IAA taxa. Finally, it seems that the absence of major extinctions and the Cenozoic cooling have been essential in making the IAA the richest marine biodiversity hotspot on Earth.

Effects of ocean warming on the fatty acid and epigenetic profile of Acartia tonsa: A multigenerational approach

The effects of climate change are becoming more prevalent, and it is important to know how copepods, the most abundant class in zooplankton, will react to changing temperatures as they are the main food source for secondary consumers. They act as key transferers of nutrients from primary producers to organisms higher up the food chain. Little is known about the effects of temperature changes on copepods on the long term, i.e., over several generations. Especially the epigenetic domain seems to be understudied and the question remains whether the nutritional value of copepods will permanently change with rising water temperatures. In this research, the effects of temperature on the fatty acid and epigenetic profiles of the abundant planktonic copepod Acartia tonsa were investigated, since we expect to see a link between these two. Indeed, changing methylation patterns helped copepods to deal with higher temperatures, which is in line with the relative abundance of the most important fatty acids, e.g., DHA. However, this pattern was only observed when temperature increased slowly. A sudden increase in temperature showed the opposite effect; Acartia tonsa did not show deviant methylation patterns and the relative abundance of DHA and other important fatty acids dropped significantly after several generations. These results suggest that local fluctuations in temperature have a greater effect on Acartia tonsa than an elevation of the global mean.

Using the Fossil Record to Understand Extinction Risk and Inform Marine Conservation in a Changing World

Understanding the long-term effects of ongoing global environmental change on marine ecosystems requires a cross-disciplinary approach. Deep-time and recent fossil records can contribute by identifying traits and environmental conditions associated with elevated extinction risk during analogous events in the geologic past and by providing baseline data that can be used to assess historical change and set management and restoration targets and benchmarks. Here, we review the ecological and environmental information available in the marine fossil record and discuss how these archives can be used to inform current extinction risk assessments as well as marine conservation strategies and decision-making at global to local scales. As we consider future research directions in deep-time and conservationpaleobiology, we emphasize the need for coproduced research that unites researchers, conservation practitioners, and policymakers with the communities for whom the impacts of climate and global change are most imminent.

Challenges and directions in analytical paleobiology

Over the last 50 years, access to new data and analytical tools has expanded the study of analytical paleobiology, contributing to innovative analyses of biodiversity dynamics over Earth's history. Despite-or even spurred by-this growing availability of resources, analytical paleobiology faces deep-rooted obstacles that stem from the need for more equitable access to data and best practices to guide analyses of the fossil record. Recent progress has been accelerated by a collective push toward more collaborative, interdisciplinary, and open science, especially by early-career researchers. Here, we survey four challenges facing analytical paleobiology from an early-career perspective: (1) accounting for biases when interpreting the fossil record; (2) integrating fossil and modern biodiversity data; (3) building data science skills; and (4) increasing data accessibility and equity. We discuss recent efforts to address each challenge, highlight persisting barriers, and identify tools that have advanced analytical work. Given the inherent linkages between these challenges, we encourage discourse across disciplines to find common solutions. We also affirm the need for systemic changes that reevaluate how we conduct and share paleobiological research.

Life rather than climate influences diversity at scales greater than 40 million years

The diversity of life on Earth is controlled by hierarchical processes that interact over wide ranges of timescales¹. Here, we consider the megaclimate regime² at scales ≥1 million years (Myr). We focus on determining the domains of 'wandering' stochastic Earth system processes ('Court Jester'³) and stabilizing biotic interactions that induce diversity dependence of fluctuations in macroevolutionary rates ('Red Queen'⁴). Using state-of-the-art multiscale Haar and cross-Haar fluctuation analyses, we analysed the global genus-level Phanerozoic marine animal Paleobiology Database record of extinction rates (E), origination rates (O) and diversity (D) as well as sea water palaeotemperatures (T). Over the entire observed range from several million years to several hundred million years, we found that the fluctuations of T, E and O showed time-scaling behaviour. The megaclimate was characterized by positive scaling exponents-it is therefore apparently unstable. E and O are also scaling but with negative exponents-stable behaviour that is biotically mediated. For D, there were two regimes with a crossover at critical timescale [Formula: see text] ≈ 40 Myr. For shorter timescales, D exhibited nearly the same positive scaling as the megaclimate palaeotemperatures, whereas for longer timescales it tracks the scaling of macroevolutionary rates. At scales of at least [Formula: see text] there is onset of diversity dependence of E and O, probably enabled by mixing and synchronization (globalization) of the biota by geodispersal ('Geo-Red Queen').

Deep-time climate legacies affect origination rates of marine genera

Biodiversity dynamics are shaped by a complex interplay between current conditions and historic legacy. The interaction of short- and long-term climate change may mask the true relationship of evolutionary responses to climate change if not specifically accounted for. These paleoclimate interactions have been demonstrated for extinction risk and biodiversity change, but their importance for origination dynamics remains untested. Here, we show that origination probability in marine fossil genera is strongly affected by paleoclimate interactions. Overall, origination probability increases by 27.8% [95% CI (27.4%, 28.3%)] when a short-term cooling adds to a long-term cooling trend. This large effect is consistent through time and all studied groups. The mechanisms of the detected effect might be manifold but are likely connected to increased allopatric speciation with eustatic sea level drop caused by sustained global cooling. We tested this potential mechanism through which paleoclimate interactions can act on origination rates by additionally examining a proxy for habitat fragmentation. This proxy, continental fragmentation, has a similar effect on origination rates as paleoclimate interactions, supporting the importance of allopatric speciation through habitat fragmentation in the deep-time fossil record. The identified complex nature of paleoclimate interactions might explain contradictory conclusions on the relationship between temperature and origination in the previous literature. Our results highlight the need to account for complex interactions in evolutionary studies both between and among biotic and abiotic factors.

Thermal niches of planktonic foraminifera are static throughout glacial-interglacial climate change

Abiotic niche lability reduces extinction risk by allowing species to adapt to changing environmental conditions in situ. In contrast, species with static niches must keep pace with the velocity of climate change as they track suitable habitat. The rate and frequency of niche lability have been studied on human timescales (months to decades) and geological timescales (millions of years), but lability on intermediate timescales (millennia) remains largely uninvestigated. Here, we quantified abiotic niche lability at 8-ka resolution across the last 700 ka of glacial-interglacial climate fluctuations, using the exceptionally well-known fossil record of planktonic foraminifera coupled with Atmosphere-Ocean Global Climate Model reconstructions of paleoclimate. We tracked foraminiferal niches through time along the univariate axis of mean annual temperature, measured both at the sea surface and at species' depth habitats. Species' temperature preferences were uncoupled from the global temperature regime, undermining a hypothesis of local adaptation to changing environmental conditions. Furthermore, intraspecific niches were equally similar through time, regardless of climate change magnitude on short timescales (8 ka) and across contrasts of glacial and interglacial extremes. Evolutionary trait models fitted to time series of occupied temperature values supported widespread niche stasis above randomly wandering or directional change. Ecotype explained little variation in species-level differences in niche lability after accounting for evolutionary relatedness. Together, these results suggest that warming and ocean acidification over the next hundreds to thousands of years could redistribute and reduce populations of foraminifera and other calcifying plankton, which are primary components of marine food webs and biogeochemical cycles.