Extinction biases inQuaternaryCaribbean lizards

Abstract

Aim Intrinsic qualities that might affect extinction risk are not well understood for lizards (suborder Lacertilia), a highly diverse and globally distributed group of reptiles (order Squamata). We use the Quaternary fossil record of Caribbean lizards to explore a commonly studied trait, body size, and its relationship to extinction. Location The Caribbean. Methods We compiled a body size database for over 300 species. We assessed whether the present‐day body size distribution of lizards differed from the body size distribution of the fossil record. We also compared body sizes of extant lizards with extinct lizards, and we used the International Union for Conservation of Nature (IUCN) Red List to evaluate whether threatened species are larger than non‐threatened species. We examined whether there were geographic or phylogenetic biases to extinction in this system. Results Quaternary extinctions were size‐biased, with a higher incidence of extinction in large‐bodied lizards; the same relationship exists between threatened and non‐threatened present‐day lizards. Biases in the fossil record do not drive this trend, as the body sizes of present‐day lizards do not differ from those preserved in the fossil record. While there is no geographic variability in extinction, we find that there is lineage specificity, as the majority of extinctions occur within the family Leiocephalidae. At the family level, size alone does not explain extinction trends for most families, but our data suggest that large‐bodied species in each family have a higher extinction risk than their smaller counterparts. Main conclusions Size‐biased extinction trends in lizards mirror phenomena in other taxonomic groups, but additional life‐history traits may play a role at the family level. We highlight the utility of fossil datasets in understanding extinction dynamics and underscore the urgency of a thorough assessment of extinction risk for insular lizards.

Extinction‐driven changes in frugivore communities on oceanic islands

“…While we acknowledge that the (sub-)fossil record is incomplete and can be biased towards particular regions, taxa or size classes (Steadman 2006, Boyer 2008, Duncan et al 2013, Kemp and Hadly 2015, our data provide a first comparative baseline for preserving and restoring plant-frugivore interactions on many islands. The underlying dataset (available from the Dryad Digital Repository) allows to identify particular frugivores and their ecological function (e.g.…”

Biases in the current knowledge of threat status in lizards, and bridging the ‘assessment gap’

“…As larger lizards have been demonstrated to have an elevated risk of extinction (Meiri, 2008;Tingley et al, 2013a;Kemp and Hadley, 2015), body size is seen as a proxy for life history traits (e.g., long-lived species with low clutch frequencies) that might inhibit a species' recovery from population declines. Furthermore, non-assessed lizard species were found to have smaller clutch sizes (corrected for female size), but equivalent longevity, to assessed species.…”

7,000 years of turnover: historical contingency and human niche construction shape the Caribbean’s Anthropocene biota

“…Paleontological studies have identified patterns of size-biased vertebrate extinction in the Caribbean [53],[10], although we are still elucidating extinction chronologies for many taxonomic groups. Large-bodied terrestrial mammals such as ground sloths disappeared prior to the Ceramic period, potentially linked to hunting or habitat alteration [10].…”

“…This introduction of potential predators and competitors links both accidental and intentional species introductions to a major extinction event in the Caribbean mammals. Similarly, the disappearance of many lizards occurred after European arrival [53],[49], likely due to impacts from introduced species.…”