Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Comparative Study
. 2014 Nov 18;111(46):16419-24.
doi: 10.1073/pnas.1406304111. Epub 2014 Oct 20.

Trait-based diversification shifts reflect differential extinction among fossil taxa

Peter J Wagner  1 , George F Estabrook  2
Affiliations
Comparative Study

Trait-based diversification shifts reflect differential extinction among fossil taxa

Peter J Wagner et al. Proc Natl Acad Sci U S A. .

Abstract

Evolution provides many cases of apparent shifts in diversification associated with particular anatomical traits. Three general models connect these patterns to anatomical evolution: (i) elevated net extinction of taxa bearing particular traits, (ii) elevated net speciation of taxa bearing particular traits, and (iii) elevated evolvability expanding the range of anatomies available to some species. Trait-based diversification shifts predict elevated hierarchical stratigraphic compatibility (i.e., primitive→derived→highly derived sequences) among pairs of anatomical characters. The three specific models further predict (i) early loss of diversity for taxa retaining primitive conditions (elevated net extinction), (ii) increased diversification among later members of a clade (elevated net speciation), and (iii) increased disparity among later members in a clade (elevated evolvability). Analyses of 319 anatomical and stratigraphic datasets for fossil species and genera show that hierarchical stratigraphic compatibility exceeds the expectations of trait-independent diversification in the vast majority of cases, which was expected if trait-dependent diversification shifts are common. Excess hierarchical stratigraphic compatibility correlates with early loss of diversity for groups retaining primitive conditions rather than delayed bursts of diversity or disparity across entire clades. Cambrian clades (predominantly trilobites) alone fit null expectations well. However, it is not clear whether evolution was unusual among Cambrian taxa or only early trilobites. At least among post-Cambrian taxa, these results implicate models, such as competition and extinction selectivity/resistance, as major drivers of trait-based diversification shifts at the species and genus levels while contradicting the predictions of elevated net speciation and elevated evolvability models.

Keywords: Cambrian; evolvability; extinction; speciation; trait-based diversification.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.
Fig. 1.
Deviations between observed and expected HSC for fossil (A) brachiopods and molluscs; (B) arthropods; (C) echinoderms; and (D) chordates. Positive numbers mean that 00→10→11 (upper right cartoon in A) sequences exceed Monte Carlo-generated expectations assuming continuous trait-independent diversification with empirically estimated origination, extinction, and sampling rates and simulated character evolution matching observed compatibility for each dataset. Negative numbers mean that 10←00→01 sequences (upper left cartoon in A) exceed those same expectations. Shades correspond to the significance of the deviations.
Fig. 2.
Fig. 2.
Deviations between observed and expected HSC over time given budding cladogenesis. Colors denote higher taxonomic group like in Fig. 1. Binomial probabilities of deviations from an expectation of 50% excess HSC are Cambrian (Cm): P = 0.584 (11 of 22); Ordovician (O): P = 0.049 (32 of 53); Silurian (S): P = 0.025 (12 of 17); Devonian (D): P = 9.6 × 10−5 (25 of 31); Carboniferous (C): P = 0.072 (11 of 17); Permian (P): P = 0.018 (11 of 15); Triassic (Tr): P = 5.3 × 10−3 (17 of 23); Jurassic (J): P = 0.026 (18 of 27); Cretaceous (K): P = 1.1 × 10−4 (36 of 48); Paleogene (Pg): P = 2.9 × 10−5 (39 of 51); and Neogene (Ng): P = 2.9 × 10−5 (12 of 15).
Fig. 3.
Fig. 3.
Associations between excess HSC and other paleontological patterns. Colors and shapes are the same as in Figs. 1 and 2. All points plot the differences between observation and expectation given continuous trait-independent diversification and no change of character space. Cartoons on the x axis idealize those deviations from the null model, with dashed lines giving expectations and solid lines giving possible patterns (D, cumulative disparity; S, richness). Gray boxes reflect predicted associations with HSC given (A) elevated net extinction, (B) elevated net speciation, and (C) elevated evolvability. (A) Observed minus expected centers of gravity for paraclades retaining 00 combinations (where 0 denotes the oldest appearing state). (B) Observed minus expected centers of gravity for whole clades. (C) Excess cumulative disparity among the first S/2 taxa in a clade of S taxa. Additional information is in Figs. 1 and 2.
See this image and copyright information in PMC

Comment in

References

    1. Lidgard S, McKinney FK, Taylor PD. Competition, clade replacement, and a history of cyclostome and cheilostome bryozoan diversity. Paleobiology. 1993;19(3):352–371.
    1. Roy K. The roles of mass extinction and biotic interaction in large-scale replacements: A reexamination using the fossil record of stromboidean gastropods. Paleobiology. 1996;22(3):436–452.
    1. Eble GJ. Contrasting evolutionary flexibility in sister groups: Disparity and diversity in Mesozoic atelostomate echinoids. Paleobiology. 2000;26(1):56–79.
    1. Lupia R, Lidgard S, Crane PR. Comparing palynological abundance and diversity: Implications for biotic replacement during the Cretaceous angiosperm radiation. Paleobiology. 1999;25(3):305–340.
    1. Sanderson MJ, Donoghue MJ. Shifts in diversification rate with the origin of angiosperms. Science. 1994;264(5165):1590–1593. - PubMed

Publication types

MeSH terms

LinkOut - more resources