The modulating role of traits on the biogeographic dynamics of chondrichthyans from the Neogene to the present

Abstract

The environmental transformations that occurred during the Neogene had profound effects on spatiotemporal biodiversity patterns, yet the modulating role of traits (i.e., physiological, ecological, and life-history traits) remains little understood. We tested this idea using the Neogene fossil record of chondrichthyans along the temperate Pacific coast of South America (TPSA). Information for georeferenced occurrences and ecological and life-history information of 38 chondrichthyan fossil genera in 42 Neogene sites was collected. Global georeferenced records were used to estimate present-day biogeographic distributions of the genera and to characterize the range of oceanographic conditions in which each genus lives as a proxy of their realized niche. Biogeographic range shifts (Neogene–present) were evaluated at regional and local scales. The role of traits as drivers of different range dynamics was evaluated using random forest models. The magnitude and direction of biogeographic range shifts were different at both spatial scales. At a regional scale, 34% of genera contracted their ranges, disappearing from the TPSA. At a local scale, a similar proportion of genera expanded and contracted their southern endpoints of distribution. The models showed a high precision at both spatial scales of analyses, but the relative importance of predictor variables differed. At a regional scale, disappearing genera tended to have a higher tolerance to salinity, lower sea surface temperature (SST) range, and smaller body sizes. At a local scale, genera contracting their ranges tended to live at greater depths, tolerate lower levels of primary productivity, and show a reduced tolerance to higher and lower SST ranges. The magnitude and direction of the changes in the range distribution were scale dependent and variable across the genera. Hence, multiple environmental exogenous factors interacted with taxon traits during the Neogene, creating a mosaic of biogeographic dynamics.

First evidence of a palaeo-nursery area of the great white shark

“…The GWS is the second most abundant chondrichthyan in the Pliocene of the eastern Pacific of South America (22%, 68 of 313 all fossil species occurrences in the region) 45 . However, this study represents the first attempt to assess the body size distribution and to identify possible palaeo-nursery areas for this species ( Fig.…”

“…This locality is also characterized by high abundance of fossil marine mammals (phocids, dugongids, dolphins and whales) 41,[54][55][56] . Furthermore, this locality is known for having a high abundance of the top predator O. megalodon 45 , which could be a potential predator for young GWS. Based on benthic foraminifers, the depositional environment of Bahia Inglesa formation has been interpreted as ranging from the littoral zone to the upper continental slope 57 .…”

Shark and ray diversity in the Tropical America (Neotropics)—an examination of environmental and historical factors affecting diversity

“…Some of the above mentioned genera were regionally extirpated from the EP (e.g., Dalatias , Pristiophoru s, Carcharias , and Isogomphodon ) or WA (e.g., Deania, Heterodontus , Taeniurops , and Aetomylaeus ), but with living representatives in one of both sides. The above mentioned fossil record of Dalatias and Isogomphodon in the EP, have been reported exclusively from the Bahía Inglesa Formation (Late Miocene–Pliocene), Atacama Region, Northern Chile ( Suárez, 2015 ; Villafaña & Rivadeneira, 2018 ). Other shark genera such as Trigonognathus , Scymnodon , Chiloscyllium , Nebrius , Iago , Chaenogaleus , Hemipristis , Paragaleus , and the family Stegostomatidae reported by Suárez (2015 , fig.…”

“…The extirpation of Dalatias , Pristiophorus , as well other marine fauna from the EP ( Rivadeneira & Marquet, 2007 ; Villafaña & Rivadeneira, 2014 ), could be correlated with the expansion of upwelling areas and the cooling of surface waters during Pliocene–Pleistocene ( Ibaraki, 1997 ; Ravelo et al, 2004 ; Lawrence, Liu & Herbert, 2006 ; Dowsett et al, 2013 ). Villafaña & Rivadeneira (2018) , suggested that the extirpation in many shark and ray species from the temperate Pacific coast of South America during the Miocene–Recent interval, was the result of a combination of their tolerance to oceanographic conditions (e.g., salinity and thermal range) and life-history traits (e.g., body size).…”

“…1 ). Although there have been attempts to approach to historical relationship between Miocene ichthyofaunas of Tropical America (e.g., Echeverry & Gallo, 2015 ), and the temperate Pacific coast of South America ( Villafaña & Rivadeneira, 2018 ), the origin and biogeographic distribution of sharks and rays diversity for the Neogene–Quaternary interval is largely unexplored. Sharks and rays can serve to address major issues on factors driving diversity and the impact of paleontological data to study diversity patterns and geographic distribution in Tropical faunas.…”