Environmental and scale-dependent evolutionary trends in the body size of crustaceans

Abstract

The ecological and physiological significance of body size is well recognized. However, key macroevolutionary questions regarding the dependency of body size trends on the taxonomic scale of analysis and the role of environment in controlling long-term evolution of body size are largely unknown. Here, we evaluate these issues for decapod crustaceans, a group that diversified in the Mesozoic. A compilation of body size data for 792 brachyuran crab and lobster species reveals that their maximum, mean and median body size increased, but no increase in minimum size was observed. This increase is not expressed within lineages, but is rather a product of the appearance and/or diversification of new clades of larger, primarily burrowing to shelter-seeking decapods. This argues against directional selective pressures within lineages. Rather, the trend is a macroevolutionary consequence of species sorting: preferential origination of new decapod clades with intrinsically larger body sizes. Furthermore, body size evolution appears to have been habitat-controlled. In the Cretaceous, reef-associated crabs became markedly smaller than those in other habitats, a pattern that persists today. The long-term increase in body size of crabs and lobsters, coupled with their increased diversity and abundance, suggests that their ecological impact may have increased over evolutionary time.

Comparative experimental taphonomy of eight marine arthropods indicates distinct differences in preservation potential

“…The diversity and body size of true crabs and lobsters first increased significantly as part of the Mesozoic decapod revolution (Klompmaker et al . , ), followed by a decrease in raw genus richness for lobsters (Schweitzer & Feldmann ) and an increase in raw brachyuran species richness (Schweitzer & Feldmann ).…”

The Rise of Jaw Protrusion in Spiny-Rayed Fishes Closes the Gap on Elusive Prey

“…The most effective response to increasing protrusion in predators is likely to be for prey to reduce the chances of visual detection. Size reduction has been previously suggested as a predation-avoidance mechanism in copepods [21], and there is evidence that reef-associated crabs decreased in size in the Cretaceous [22]. Indeed, on modern coral reefs, the mean size of crustaceans is only 0.8 mm [23].…”

Coevolution of post‐Palaeozoic arthropod basibiont diversity and encrusting bryozoan epibiont diversity?

“…In regard to the effect of intra-family exoskeleton surface area variation, each arthropod basibiont does not provide the same target area for bryozoan larval settlement. Klompmaker et al (2015) found that maximum, mean and median body size increased for crabs and lobsters over the course of the Mesozoic. They argued that this long-term increase in body size of crabs and lobsters, coupled with their increased diversity and abundance, suggests that their ecological impact may have increased over evolutionary time.…”

“…anthropogenic greenhouse gas emissions and global warming). Studies on arthropods (Minelli et al 2013;Klompmaker et al 2015) and bryozoans (McKinney & Jackson 1989;Taylor & Waeschenbach 2015) often use biodiversity time series data to infer evolutionary causality. When trying to interpret biodiversity time series data, it is important to keep in mind that temporal correlation does not necessarily imply causation (Hannisdal & Liow 2018).…”