Morphological divergence in giant fossil dormice

Insular gigantism—evolutionary increases in body size from small-bodied mainland ancestors—is a conceptually significant, but poorly studied, evolutionary phenomenon. Gigantism is widespread on Mediterranean islands, particularly among fossil and extant dormice. These include an extant giant population of Eliomys quercinus on Formentera, the giant Balearic genus † Hypnomys and the exceptionally large † Leithia melitensis of Pleistocene Sicily. We quantified patterns of cranial and mandibular shape and their relationships to head size (allometry) among mainland and insular dormouse populations, asking to what extent the morphology of island giants is explained by allometry. We find that gigantism in dormice is not simply an extrapolation of the allometric trajectory of their mainland relatives. Instead, a large portion of their distinctive cranial and mandibular morphology resulted from the population- or species-specific evolutionary shape changes. Our findings suggest that body size increases in insular giant dormice were accompanied by the evolutionary divergence of feeding adaptations. This complements other evidence of ecological divergence in these taxa, which span predominantly faunivorous to herbivorous diets. Our findings suggest that insular gigantism involves context-dependent phenotypic modifications, underscoring the highly distinctive nature of island faunas.

Download Full-text

A uni- and multivariate analysis approach to reveal sexual size dimorphism in Iranian populations of Hypera postica (Coleoptera: Curculionidae)

Biologia ◽

10.1515/biolog-2015-0137 ◽

2015 ◽

Vol 70 (9) ◽

pp. 1228-1233 ◽

Cited By ~ 3

Author(s):

Ehsan Sanaei ◽

Marjan Seiedy ◽

Farzaneh Momtazi

Keyword(s):

Body Size ◽

Sexual Size Dimorphism ◽

Egg Laying ◽

Morphological Divergence ◽

High Fecundity ◽

Hypera Postica ◽

Size Dimorphism ◽

Female Body Size ◽

Divergence Pattern ◽

Iranian Populations

Abstract Body size dimorphism between genders is a commonly observed phenomenon in insects, usually manifested in larger female body size. Sexual Size Dimorphism (SSD) varies from species to species, the degree and direction influenced by certain evolutionary pressures. Intraspecific variation in SSD may also occur between populations. The Hypera postica (Gyllenhal, 1813) is a well-known alfalfa plant pest that shows a degree of morphological divergence in its populations. The female alfalfa weevils are very fecund and have a larger body size compared to males. To improve our knowledge on magnitude and direction of SSD in alfalfa weevil, we studied 200 specimens of H. postica from four Iranian populations (Karaj1, Karaj2, Tuyserkan and Jovein). 10 morphological variables from three external anatomic parts (pronotum, elytra and rostrum) and 45 ratio characters were statistically analyzed in order to determine the amount of SSD in Iranian populations. In addition we investigated for morphological divergence pattern in mentioned populations. The results of this study show that a low degree of morphological divergence occurs in Iranian populations. Measured variables indicate that the SSD pattern of H. postica is compatible with the Rensch’s rule, and is related to high fecundity of females and a lack of strong sexual selection. Also it is mentioned that the larger rostrum in females may correspond to its unique role in egg laying.

Download Full-text

Explaining variability in parasite aggregation levels among host samples

Parasitology ◽

10.1017/s0031182012002053 ◽

2013 ◽

Vol 140 (4) ◽

pp. 541-546 ◽

Cited By ~ 85

Author(s):

ROBERT POULIN

Keyword(s):

Body Size ◽

Strong Relationship ◽

Host Susceptibility ◽

Helminth Parasites ◽

Susceptibility To Infection ◽

Host Body ◽

Parasite Aggregation ◽

Using Data ◽

Species Specific ◽

Host Body Size

SUMMARYAggregated distributions among individual hosts are a defining feature of metazoan parasite populations. Heterogeneity among host individuals in exposure to parasites or in susceptibility to infection is thought to be the main factor generating aggregation, with properties of parasites themselves explaining some of the variability in aggregation levels observed among species. Here, using data from 410 samples of helminth parasites on fish hosts, I tested the contribution of (i) within-sample variation in host body size, taken as a proxy for variability in host susceptibility, and (ii) parasite taxon and developmental stage, to the aggregated distribution of parasites. Log-transformed variance in numbers of parasites per host was regressed against log mean number across all samples; the strong relationship (r2 = 0·88) indicated that aggregation levels are tightly constrained by mean infection levels, and that only a small proportion of the observed variability in parasite aggregation levels remains to be accounted for by other factors. Using the residuals of this regression as measures of ‘unexplained’ aggregation, a mixed effects model revealed no significant effect of within-sample variation in host body size or of parasite taxon or stage (i.e. juvenile versus adult) on parasite aggregation level within a sample. However, much of the remaining variability in parasite aggregation levels among samples was accounted for by the number of individual hosts examined per sample, and species-specific and study-specific effects reflecting idiosyncrasies of particular systems. This suggests that with most differences in aggregation among samples already explained, there may be little point in seeking universal causes for the remaining variation.

Download Full-text

Convergence in reduced body size, head size, and blood glucose in three island reptiles

Ecology and Evolution ◽

10.1002/ece3.4171 ◽

2018 ◽

Vol 8 (12) ◽

pp. 6169-6182 ◽

Cited By ~ 5

Author(s):

Amanda M. Sparkman ◽

Amanda D. Clark ◽

Lilly J. Brummett ◽

Kenneth R. Chism ◽

Lucia L. Combrink ◽

...

Keyword(s):

Body Size ◽

Blood Glucose ◽

Head Size ◽

Reduced Body

Download Full-text

Evolutionary Divergence of Adult Body Size and Juvenile Growth in Sympatric Subpopulations of a Top Predator in Aquatic Ecosystems

The American Naturalist ◽

10.1086/681597 ◽

2015 ◽

Vol 186 (1) ◽

pp. 98-110 ◽

Cited By ~ 18

Author(s):

Petter Tibblin ◽

Anders Forsman ◽

Per Koch-Schmidt ◽

Oscar Nordahl ◽

Peter Johannessen ◽

...

Keyword(s):

Body Size ◽

Aquatic Ecosystems ◽

Evolutionary Divergence ◽

Juvenile Growth ◽

Top Predator ◽

Adult Body Size ◽

Adult Body

Download Full-text

Can snakes use yolk reserves to maximize body size at hatching?

Current Zoology ◽

10.1093/cz/zoy098 ◽

2018 ◽

Vol 65 (6) ◽

pp. 627-631 ◽

Cited By ~ 1

Author(s):

Yan-Fu Qu ◽

Shu-Zhan Zhao ◽

Xu-Fei Jiang ◽

Long-Hui Lin ◽

Xiang Ji

Keyword(s):

Body Size ◽

Body Mass ◽

Tail Length ◽

Linear Size ◽

Egg Mass ◽

Fat Bodies ◽

Free Body ◽

Species Specific ◽

Naja Atra

Abstract We experimentally miniaturized freshly laid eggs of the Chinese cobra Naja atra (Elapidae) by removing ∼10% and ∼20% of original yolk. We tested if yolk-reduced eggs would produce 1) normal-sized hatchlings with invariant yolk-free body mass (and thus invariant linear size) but dramatically reduced or even completely depleted residual yolk, 2) smaller hatchlings with normal-sized residual yolk but reduced yolk-free body mass, or 3) smaller hatchlings of which both yolk-free body mass and residual yolk are proportionally reduced. Yolk quantity affected hatchling linear size (both snout-vent length and tail length) and body mass. However, changes in yolk quantity did not affect incubation length or any hatchling trait examined after accounting for egg mass at laying (for control and sham-manipulated eggs) or after yolk removal (for manipulated eggs). Specifically, yolk-reduced eggs produced hatchlings of which all major components (carcass, residual yolk, and fat bodies) were scaled down proportionally. We show that snakes cannot use yolk reserves to maximize their body size at hatching. Furthermore, our data also suggest that the partitioning of yolk in embryonic snakes is species-specific.

Download Full-text

Risk Factors for Development of Canine and Human Osteosarcoma: A Comparative Review

Veterinary Sciences ◽

10.3390/vetsci6020048 ◽

2019 ◽

Vol 6 (2) ◽

pp. 48 ◽

Cited By ~ 11

Author(s):

Kelly M. Makielski ◽

Lauren J. Mills ◽

Aaron L. Sarver ◽

Michael S. Henson ◽

Logan G. Spector ◽

...

Keyword(s):

Risk Factors ◽

Body Size ◽

Bone Cancer ◽

Domestic Dogs ◽

Comparative Approach ◽

Important Species ◽

Human Osteosarcoma ◽

Comparative Review ◽

Cellular Replication ◽

Species Specific

Osteosarcoma is the most common primary tumor of bone. Osteosarcomas are rare in humans, but occur more commonly in dogs. A comparative approach to studying osteosarcoma has highlighted many clinical and biologic aspects of the disease that are similar between dogs and humans; however, important species-specific differences are becoming increasingly recognized. In this review, we describe risk factors for the development of osteosarcoma in dogs and humans, including height and body size, genetics, and conditions that increase turnover of bone-forming cells, underscoring the concept that stochastic mutational events associated with cellular replication are likely to be the major molecular drivers of this disease. We also discuss adaptive, cancer-protective traits that have evolved in large, long-lived mammals, and how increasing size and longevity in the absence of natural selection can account for the elevated bone cancer risk in modern domestic dogs.

Download Full-text

Factors driving sexual dimorphism and colour variability in the Achala Copper Lizard (Pristidactylus achalensis), an endemic species to the highland mountains in central Argentina

Canadian Journal of Zoology ◽

10.1139/cjz-2019-0293 ◽

2020 ◽

Vol 98 (6) ◽

pp. 377-389

Author(s):

S. Naretto ◽

M. Chiaraviglio

Keyword(s):

Sex Differences ◽

Spatial Distribution ◽

Body Size ◽

Sexual Dimorphism ◽

Endemic Species ◽

Morphological Changes ◽

Head Size ◽

Head Width ◽

Temporal And Spatial Distribution ◽

Central Argentina

The intensity of mating competition varies according to the temporal and spatial distribution of individuals. Measuring sexual dimorphism over time and interpreting the association between individuals is therefore important if we aim to understand how sexual traits are influenced. We examined sex differences in the Achala Copper Lizard (Pristidactylus achalensis (Gallardo, 1964)), an endemic species from the highest part of mountains of central Argentina. Over 4 years, we explored sex-specific variation in body size, head size, interlimb length, and body colouration. Furthermore, we evaluated how these traits varied temporally, and we also explored whether the spatial distribution of individuals is explained by variation in these traits. We found that P. achalensis is a species with sexual dimorphism in multiple characters, including body size, head size, and colouration. Interestingly, some traits related to mating, such as head width, show a temporal variability in both sexes, whereas other traits, such as colouration, varies seasonally only in males. Our results underline the intriguing possibility of seasonal morphological changes related to mating, and more broadly that sex differences are influenced by sexual selection pressures mediated by temporal variation in mate competition.

Download Full-text

Body Size and Shape Changes and the Risk of Diabetes in the Diabetes Prevention Program

Diabetes ◽

10.2337/db07-0009 ◽

2007 ◽

Vol 56 (6) ◽

pp. 1680-1685 ◽

Cited By ~ 76

Author(s):

W. Y. Fujimoto ◽

K. A. Jablonski ◽

G. A. Bray ◽

A. Kriska ◽

E. Barrett-Connor ◽

...

Keyword(s):

Body Size ◽

Prevention Program ◽

Diabetes Prevention ◽

Diabetes Prevention Program ◽

Size And Shape ◽

Shape Changes

Download Full-text

Body size and trophic divergence of two large sympatric elapid snakes (Notechis scutatus and Austrelaps superbus) (Serpentes:Elapidae) in Tasmania

Australian Journal of Zoology ◽

10.1071/zo12004 ◽

2012 ◽

Vol 60 (3) ◽

pp. 159 ◽

Cited By ~ 2

Author(s):

S. Fearn ◽

J. Dowde ◽

D. F. Trembath

Keyword(s):

Body Size ◽

High Frequency ◽

Field Data ◽

Trophic Ecology ◽

Competitive Exclusion ◽

Head Size ◽

Large Prey ◽

Potential Prey ◽

Island State ◽

Species Being

Tiger snakes (Notechis scutatus) and lowland copperheads (Austrelaps superbus) are both large viviparous elapid snakes confined to the cooler, mesic regions of southern Australia. In spite of both species being common and widespread in the island state of Tasmania, no quantified studies on the trophic ecology of these two snakes from the main island has been published. During a two-year period we collected field data from 127 adult A. superbus and 74 adult N. scutatus from throughout eastern Tasmania. For both species, males were larger than females with respect to all measured parameters, including mass and head size. Reproduction in females was strongly seasonal and clutch size was not related to maternal body size. N. scutatus has a larger head than A. superbus and consequently ingests both small and large prey. N. scutatus in our study displayed the most catholic diet of any Australian elapid studied to date and consumed mammals (possum, bandicoot, antechinus, rats, mice), birds (fairy wrens), fish (eel, trout) and frogs. A. superbus shows a more specialist diet of large volumes of predominately ectothermic prey (frogs, lizards, snakes) even at maximal sizes and was more likely to contain ingested prey than specimens of N. scutatus. Distinctive rodent bite scars were common on N. scutatus but rare on A. superbus. The high frequency of rodent bite scars on N. scutatus further supports our findings of a primarily endothermic diet for mature specimens. We suggest that significant differences in head size, and hence diet, as well as a taxonomically diverse suite of potential prey in Tasmania allow both these large snakes to coexist in sympatry and avoid interspecific competitive exclusion.

Download Full-text

Seasonal changes in body size and oil sac volume of three planktonic copepods, Paracalanus parvus (Claus, 1863), Pseudocalanus newmani Frost, 1989 and Oithona similis Claus, 1866, in a temperate embayment: what controls their seasonality?

Crustaceana ◽

10.1163/15685403-00003287 ◽

2014 ◽

Vol 87 (3) ◽

pp. 364-375 ◽

Cited By ~ 2

Author(s):

Daichi Arima ◽

Atsushi Yamaguchi ◽

Yoshiyuki Abe ◽

Kohei Matsuno ◽

Rui Saito ◽

...

Keyword(s):

Body Size ◽

Seasonal Changes ◽

Primary Energy ◽

Specific Pattern ◽

Peak Period ◽

Oithona Similis ◽

Warm Summer ◽

Cold Spring ◽

Species Specific ◽

Paracalanus Parvus

Seasonal changes in body size (prosome length: PL) and oil sac volume (OSV) of the three most numerically abundant copepods in Ishikari Bay, northern Sea of Japan, Paracalanus parvus (Claus, 1863), Pseudocalanus newmani Frost, 1989 and Oithona similis Claus, 1866, were studied using monthly samples collected through vertical hauls of a 100-μm mesh NORPAC net from March, 2001 to May, 2002. Seasonal changes in PL were common for the three species and were more pronounced during a cold spring. PL was negatively correlated with temperature, and this relationship was described well using the Bělehrádek equation. Seasonal changes in OSV exhibited a species-specific pattern, i.e., OSV was greater during a warm summer for P. parvus and was greater during a cold spring for P. newmani and O. similis. The OSV peak period corresponded with the optimal thermal season of each species. The relative OSV to prosome volume of the small copepods (0.6-0.8%) was substantially lower than that of the large copepods (20-32%). These facts suggest that the oil sac of small copepods is not used for overwintering or diapauses or during periods of food scarcity, but is instead used as the primary energy source for reproduction, which occurs during the optimum thermal season of each species.

Download Full-text