THE EARLIEST-KNOWN MUSTELID IN NORTH AMERICA AND THE CONVERGENT EVOLUTION OF SMALL BODY SIZE IN MUSTELIDAE

Convergent evolution of small body size occurs across many vertebrate clades and may reflect an evolutionary response to shared selective pressures. However it remains unclear if other aspects of phenotype undergo convergent evolution in miniaturized lineages. Here we present a comparative analysis of body size and shape evolution in marine angelfishes (Pomacanthidae), a reef fish family characterized by repeated transitions to small body size. We ask if lineages that evolve small sizes show convergent evolution in body shape. Our results reveal that angelfish lineages evolved three different stable size optima with one corresponding to the group of pygmy angelfishes ( Centropyge ). Then, we test if the observed shifts in body size are associated with changes to new adaptive peaks in shape. Our data suggest that independent evolution to small size optima have induced repeated convergence upon deeper body and steeper head profile in Centropyge . These traits may favour manoeuvrability and visual awareness in these cryptic species living among corals, illustrating that functional demands on small size may be related to habitat specialization and predator avoidance. The absence of shape convergence in large marine angelfishes also suggests that more severe requirements exist for small than for large size optima.

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Evaluating hypotheses for the early diversification of dinosaurs

Earth and Environmental Science Transactions of the Royal Society of Edinburgh ◽

10.1017/s1755691011020068 ◽

2010 ◽

Vol 101 (3-4) ◽

pp. 397-426 ◽

Cited By ~ 49

Author(s):

Randall B. Irmis

Keyword(s):

Body Size ◽

Species Diversity ◽

North America ◽

Relative Abundance ◽

Evolutionary History ◽

Small Body ◽

Small Body Size ◽

Early Diversification ◽

Complex Process ◽

Extinction Event

ABSTRACTMany hypotheses have been proposed for the rise of dinosaurs, but their early diversification remains poorly understood. This paper examines the occurrences, species diversity and abundance of early dinosaurs at both regional and global scales to determine patterns of their early evolutionary history. Four main patterns are clear: (1) sauropodomorph dinosaurs became abundant during the late Norian–Rhaetian of Gondwana and Europe; (2) Triassic dinosaurs of North America have low species diversity and abundance until the beginning of the Jurassic; (3) sauropodomorphs and ornithischians are absent in the Triassic of North America; and (4) ornithischian dinosaurs maintain low species diversity, relative abundance and small body size until the Early Jurassic. No one hypothesis fully explains these data. There is no evidence for a Carnian–Norian extinction event, but sauropodomorphs did become abundant during the Norian in some assemblages. No clear connection exists between palaeoenvironment and early dinosaur diversity, but environmental stress at the Triassic–Jurassic boundary is consistent with changes in North American dinosaur assemblages. Elevated growth rates in dinosaurs are consistent with the gradual phyletic increase in body size. This study demonstrates that early dinosaur diversification was a complex process that was geographically diachronous and probably had several causes.

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First records of Parergodrilus heideri (Annelida: "Polychaeta") from North America

Zootaxa ◽

10.11646/zootaxa.3498.1.5 ◽

2012 ◽

Vol 3498 (1) ◽

pp. 81 ◽

Cited By ~ 2

Author(s):

JIŘÍ SCHLAGHAMERSKÝ ◽

LEE E. FRELICH

Keyword(s):

Body Size ◽

North America ◽

Small Body ◽

The Other ◽

Small Body Size ◽

Free Living ◽

Soil Mesofauna ◽

The Family ◽

Terrestrial Habitats

Parergodrilus heideri Reisinger, 1925 is one of two species of the family Parergodrilidae (together with the marine litoral, interstitial species Stygocapitella subterranea Knöllner, 1934) and one of only two truly soil-dwelling “polychaetes” (the other being Hrabeiella periglandulata Pižl and Chalupský, 1984) that are predominantly known from terrestrial habitats (Reisinger 1925, 1960; Römbke and Jans 1991; Chalupský 1992; Graefe 1993; Rota 1997, 1998; Purschke 1999; Rota et al. 2001; Beylich and Graefe 2007; Martinez-Ansemil and Parapar 2009; Rota et al. 2010). Due to its small body size (adults up to 1 mm) and sensitivity to dessication, the species has usually been found by researchers using some type of wet extraction for soil mesofauna, such as enchytraeids and free-living flatworms (“turbellarians”). However, due to its similar chaetae, Parergodrilus heideri can be easily mistaken for a freshly hatched enchytraeid, even by enchytraeid specialists without experience with this species.

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Adaptive significance of small body size under poor socio-economic conditions in southern Peru

American Journal of Physical Anthropology ◽

10.1002/ajpa.1330390216 ◽

1973 ◽

Vol 39 (2) ◽

pp. 255-261 ◽

Cited By ~ 42

Author(s):

A. Roberto Frisancho ◽

Jorge Sanchez ◽

Danilo Pallardel ◽

Lizandro Yanez

Keyword(s):

Body Size ◽

Small Body ◽

Adaptive Significance ◽

Economic Conditions ◽

Small Body Size ◽

Southern Peru

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Decline of Cane Toad, Bufo-Marinus, Populations - Status of Urban Toads

Wildlife Research ◽

10.1071/wr9860597 ◽

1986 ◽

Vol 13 (4) ◽

pp. 597 ◽

Cited By ~ 4

Author(s):

WJ Freeland ◽

BLJ Delvinquier ◽

B Bonnin

Keyword(s):

Body Size ◽

Urban Population ◽

Small Body ◽

Rural Populations ◽

Small Body Size ◽

High Food ◽

Cane Toad ◽

Water Shortages ◽

Toad Bufo ◽

Low Rate

Cane toads from an urban population in Townsville, Qld, exhibit poor body condition and small body size, as do toads in populations around Townsville which have declined in numbers. The small body size and poor condition are associated with a high food intake and a low rate of parasitism. The results suggest that decline of rural populations is not a product of parasitism, or food and or water shortages related to unusually adverse seasonal conditions. Populations of cane toads around Townsville declined more than 3 years before this study.

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