Growth and sexual size dimorphism in Alberta populations of the eastern short-horned lizard, Phrynosoma douglassi brevirostre

1985 ◽  
Vol 63 (1) ◽  
pp. 139-154 ◽  
Author(s):  
G. Lawrence Powell ◽  
Anthony P. Russell
Keyword(s):  
Growth Model ◽  
Sexual Difference ◽  
Sexual Size Dimorphism ◽  
Growth Models ◽  
Tail Length ◽  
Growth Patterns ◽  
Head Width ◽  
Adult Size ◽  
Adult Males ◽  
Size Dimorphism

Alberta populations of Phrynosoma douglassi brevirostre display marked sexual size dimorphism, adult females being considerably larger than adult males. Discriminant analyses of whole mensural characters and of scaled mensural characters indicate that this dimorphism is present from birth, although it is more strongly expressed after sexual maturity. Recapture data were used to generate modified logistic by weight growth models for snout–vent length (SVL), and allometric models for each sex were generated for growth in tail length, head length, and head width. The SVL growth model for females indicates delayed maturity leading to greater adult size, an expected feature of a female viviparine. The SVL growth model for males indicates that growth ceases sooner than in females, resulting in a smaller adult size. This is possibly a result of male dispersal competition, an hypothesis further borne out by the results of a preliminary analysis of mobility in the two sexes, and may also be influenced by intersexual dietary competition. Differences in head dimensions between the sexes are a function of the differences in SVL at adulthood, but there is a significant sexual difference in the allometric relationship of tail length to SVL. No difference in the growth patterns and adult size of either sex was found to exist over the range in Alberta.

Reproductive isolation and sex-role reversal in two sympatric sand-dwelling wolf spiders of the genus Allocosa

2008 ◽  
Vol 86 (7) ◽  
pp. 648-658 ◽  
Author(s):  
A. Aisenberg ◽  
F. G. Costa
Keyword(s):  
Reproductive Isolation ◽  
Sexual Size Dimorphism ◽  
Sex Role ◽  
Wolf Spider ◽  
Coastal Dunes ◽  
Pitfall Trap ◽  
Role Reversal ◽  
Adult Size ◽  
Wolf Spiders ◽  
Size Dimorphism

Allocosa brasiliensis (Petrunkevitch, 1910) is a nocturnal wolf spider inhabitant of coastal dunes. Pitfall-trap data suggested the occurrence of two sympatric and synchronic morphs, with differences in adult size and abdominal design (minor and major morphs). Previous studies performed with the major morph of A. brasiliensis, postulated courtship-role and sexual size dimorphism reversal for this spider. In the present study, we compare data on development and morphology and test reproductive isolation between morphs of A. brasiliensis, with the hypotheses that the two morphs are reproductively isolated and both show courtship-role reversal. As had been reported for the major morph of A. brasiliensis, the minor-morph females approached the burrows of minor-morph males, entered, initiated courtship, and after copulation, males closed their burrows with female cooperation from the inside. Females did not court or copulate with males belonging to the other morph and, in two cases, major-morph females cannibalised minor-morph males. Morphometrical and developmental data showed differences between morphs. The occurrence of copulation only between individuals of the same morph confirm reproductive isolation, supporting the occurrence of two species. Morphological and behavioural data are consistent with courtship-role-reversal hypotheses for the minor morph, constituting the second report in spiders of this atypical behaviour.

Growth of Grey Kangaroos and the Reliablility of Age Determination from Body Measurements III. Interspecific Comparisions between Eastern and Western Grey Kangaroos, Macropus giganteus and M. fuliginosus

1984 ◽  
Vol 11 (1) ◽  
pp. 11 ◽  
Author(s):  
WE Poole ◽  
SM Carpenter ◽  
JT Wood
Keyword(s):  
Growth Models ◽  
Age Determination ◽  
Growth Patterns ◽  
Adult Size ◽  
Body Measurements ◽  
Foot Length ◽  
The Common ◽  
Rates Of Growth ◽  
Body Parameters

Seven body measurements were taken at regular intervals throughout life from both male and female eastern and western grey kangaroos. Evaluation of the reliability of criteria for determination of age and some aspects of the growth models for the two species were presented in earlier papers in this series. In this paper the common patterns and relationships between species in the growth characteristics of their body parameters are described and analysed. Comparison is made between species and sexes of rates of growth and size attained both within the pouch and following vacation of the pouch. Head, arm, leg and foot length were important discriminators, particularly when contrasted in various ways to summarize different body proportions. The insular form M.f. fuliginosus readily separated from the mainland forms, and M.f. ocydromus showed some differences which were related to its longer pouch life. Hybrid animals showed growth patterns intermediate to those of their parents. Sexual dimorphism in patterns ofgrowth was not detected during pouch life but was exhibited by all species after the young vacated the pouch and grew towards their full adult size.

Sexual difference in habitat use of Texas map turtles (Emydidae: Graptemys versa) and its relationship to size dimorphism and diet

2003 ◽  
Vol 81 (7) ◽  
pp. 1185-1191 ◽  
Author(s):  
Peter V Lindeman
Keyword(s):  
Body Size ◽  
Habitat Use ◽  
Sexual Difference ◽  
Young Female ◽  
Sexual Differences ◽  
Adult Males ◽  
Size Dimorphism ◽  
Young Females ◽  
Alternative Hypotheses ◽  
Map Turtles

Sexual differences in habitat use of map turtles (Graptemys spp.) have been attributed to differences in swimming ability as influenced by body size, because females are much larger than males, or to sexual differences in diet. Captures of young female Graptemys versa, which had body sizes similar to those of adult males but diet and trophic morphology more similar to those of larger females, allowed testing of these alternative hypotheses. A variety of single habitat variables measured at the sites of capture performed poorly in separating the three groups of turtles, but multivariate analysis and variables relating to position within the stream produced greater separation, indicating that complex combinations of factors probably influence habitat use. Young females were more similar in their habitat use to large females than to males, and their diet was also more similar to that of larger females, due primarily to the quantities of mollusks consumed. The data supported the hypothesis that habitat separation was the result of dietary rather than body size differences. While dietary differences are probably facilitated by sexual size dimorphism, they may not be the ultimate selective force that produced the size dimorphism.

Age and growth estimates of the jumbo flying squid (Dosidicus gigas) off Peru

2019 ◽  
Vol 32 ◽  
pp. 7
Author(s):  
Carlos Goicochea-Vigo ◽  
Enrique Morales-Bojórquez ◽  
Viridiana Y. Zepeda-Benitez ◽  
José Ángel Hidalgo-de-la-Toba ◽  
Hugo Aguirre-Villaseñor ◽  
...  
Keyword(s):  
Growth Model ◽  
Growth Pattern ◽  
Growth Models ◽  
Information Criterion ◽  
Growth Patterns ◽  
Age And Growth ◽  
Dosidicus Gigas ◽  
Asymptotic Growth ◽  
Schnute Model ◽  
Gompertz Growth Model

Mantle length (ML) and age data were analyzed to describe the growth patterns of the flying jumbo squid, Dosidicus gigas, in Peruvian waters. Six non-asymptotic growth models and four asymptotic growth models were fitted. Length-at-age data for males and females were analysed separately to assess the growth pattern. Multi-model inference and Akaike's information criterion were used to identify the best fitting model. For females, the best candidate growth model was the Schnute model with L∞ = 106.96 cm ML (CI 101.23–110.27 cm ML, P < 0.05), age at growth inflection 244.71 days (CI 232.82–284.86 days, P < 0.05), and length at growth inflection 57.26 cm ML (CI 55.42–58.51 cm ML, P < 0.05). The growth pattern in males was best described by a Gompertz growth model with L∞ = 127.58 cm ML (CI 115.27–131.80 cm ML, P < 0.05), t0 = 21.8 (CI 20.06–22.41, P < 0.05), and k = 0.007 (CI 0.006–0.007, P < 0.05). These results contrast with the growth model previously reported for D. gigas in the region, where the growth pattern was identified as non-asymptotic.

Offspring growth and parental care in sexually dimorphic Nazca boobies (Sula granti)

2007 ◽  
Vol 85 (6) ◽  
pp. 686-694 ◽  
Author(s):  
H.M. Townsend ◽  
T.J. Maness ◽  
D.J. Anderson
Keyword(s):  
Sexual Size Dimorphism ◽  
Poor Performance ◽  
Sexually Dimorphic ◽  
Adult Males ◽  
Parental Effort ◽  
Size Dimorphism ◽  
Sula Granti ◽  
More Care ◽  
Mean Size ◽  
Specific Food

A review of studies on nestling bird food requirements indicates that degree of sexual size dimorphism reliably predicts disparity in sex-specific food requirements, but that parents often fail to meet the excess requirement of the larger sex. We studied a population of Nazca boobies ( Sula granti Rothschild, 1902), a sexually dimorphic pelagic seabird, to determine whether parents provide more care to daughters, the larger sex. Daughters grew to a larger size than did sons during the nestling period, but did not reach the mean size of adult females, while sons exceeded the size of adult males. Estimates of parental effort exerted for sons versus daughters indicated similar levels of effort, and that females fledged in poorer condition than males did in the study year, one of intermediate breeding conditions. Results from another study conducted during better breeding conditions indicated little limitation on growth of either sex. Together, these studies are consistent with a ceiling on parental effort in a long-lived species that allows consistent self-maintenance for parents, but causes poor performance in the costlier sex under poor breeding conditions. Complementary studies of short-lived species are needed to evaluate our suggested linkage between parental effort, self-maintenance, and sexual size dimorphism.

scholarly journals A New Flexible Sigmoidal Growth Model

Symmetry ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 204 ◽  
Author(s):  
Liying Cao ◽  
Pei-Jian Shi ◽  
Lin Li ◽  
Guifen Chen
Keyword(s):  
Growth Rate ◽  
Growth Model ◽  
Growth Models ◽  
Differential Evolution Algorithm ◽  
Growth Patterns ◽  
Growth Data ◽  
Ecological Processes ◽  
Maximum Biomass ◽  
Sigmoidal Growth ◽  
Growth Of Animals

Biological growth is driven by numerous functions, such as hormones and mineral nutrients, and is also involved in various ecological processes. Therefore, it is necessary to accurately capture the growth trajectory of various species in ecosystems. A new sigmoidal growth (NSG) model is presented here for describing the growth of animals and plants when the assumption is that the growth rate curve is asymmetric. The NSG model was compared with four classic sigmoidal growth models, including the logistic equation, Richards, Gompertz, and ontogenetic growth models. Results indicated that all models fit well with the empirical growth data of 12 species, except the ontogenetic growth model, which only captures the growth of animals. The estimated maximum asymptotic biomass wmax of plants from the ontogenetic growth model was not reliable. The experiment result shows that the NSG model can more precisely estimate the value and time of reaching maximum biomass when growth rate becomes close to zero near the end of growth. The NSG model contains three other parameters besides the value and time of reaching maximum biomass, and thereby, it can be difficult to assign initial values for parameterization using local optimization methods (e.g., using Gauss–Newton or Levenberg–Marquardt methods). We demonstrate the use of a differential evolution algorithm for resolving this issue efficiently. As such, the NSG model can be applied to describing the growth patterns of a variety of species and estimating the value and time of achieving maximum biomass simultaneously.

scholarly journals Sexual size dimorphism and female reproduction in the white-striped grass lizard Takydromus wolteri

2012 ◽  
Vol 58 (2) ◽  
pp. 236-243 ◽  
Author(s):  
Laigao Luo ◽  
Yilian Wu ◽  
Zhuyuan Zhang ◽  
Xuefeng Xu
Keyword(s):  
Egg Size ◽  
Reproductive Output ◽  
Sexual Size Dimorphism ◽  
Tail Length ◽  
Reproductive Traits ◽  
Life History Variation ◽  
Female Reproduction ◽  
Size Dimorphism ◽  
First Clutch ◽  
Female Reproductive Traits

Abstract Sexual size dimorphism (SSD) has long attracted the attention of biologists, and life-history variation is thought to play an important role in the evolution of SSD. Here we quantified SSD and female reproductive traits to identify potential associations between SSD and female reproduction in the white-striped grass lizard Takydromus wolteri. In a population from Chuzhou, China, the largest male and female were 53.0 mm and 57.5 mm in snout-vent length (SVL), respectively. Females were larger in SVL and abdomen length, whereas males were larger in head size and tail length. Females produced up to five clutches of eggs during the breeding season, with large females producing more clutches and more eggs per clutch than small ones. As a result, large females had a higher annual fecundity and reproductive output. Egg size was positively correlated with maternal SVL in the first clutch, but not in subsequent clutches. These results suggest that T. wolteri is a species with female-biased SSD, and that fecundity selection, in which large females have higher fecundity due to their higher capacity for laying eggs, is likely correlated with the evolution of SSD in this species [Current Zoology 58 (2): 236–243, 2012].

Sexual size dimorphism in relation to age and growth based on skeletochronological analysis in a Tibetan frog

2009 ◽  
Vol 30 (3) ◽  
pp. 351-359 ◽  
Author(s):  
Xin Lu ◽  
Xiaoyan Ma
Keyword(s):  
Growth Rate ◽  
Cross Sections ◽  
Sexual Difference ◽  
Sexual Size Dimorphism ◽  
Population Level ◽  
Age And Growth ◽  
Size Difference ◽  
Size Dimorphism ◽  
Asymptotic Size ◽  
Central Tibet

AbstractThe number of lines of arrested growth (LAGs) in diaphyseal cross-sections of phalanges or femora was used to assess individual age and growth of 612 Nanorana parkeri, including 363 males, 143 females, 70 juveniles, and 36 tadpoles, in a population from central Tibet, China. The oldest immature frogs had an age of 6 years; both the youngest sexually mature males and females were 3 years old. However, the majority of individuals bred for the first time at 5 years in males and 6 years in females. Females had greater average age (6.27 years) and lifespan (11 years) than males (5.72 and 10 years). At the population level, females, on average, were significantly larger in body length (40.3 mm) than males (37.0 mm). However, the significant size difference only occurred when both sexes were over 6 years old, at which most frogs attained maturity. Growth curve and growth rate estimated for each sex based on a von Bertalanffy model showed that females had a larger asymptotic size (54.2 mm) but smaller growth coefficient k (0.16) than males (40.0 mm, 0.37), and that females had greater growth rate than males in all age classes, except at metamorphosis. According to these results, we concluded that the sexual difference of growth between pre- and post-maturation periods contributed to the age-specific sexual size dimorphism of N. parkeri.

Sexual size dimorphism and microhabitat use of the orange-tail skink (Gongylomorphus spp.) on Flat Island, Mauritius: conservation implications

2008 ◽  
Vol 29 (3) ◽  
pp. 349-359 ◽  
Author(s):  
Toby Ross ◽  
Diana Bell ◽  
Carl Jones ◽  
Angelo Pernetta
Keyword(s):  
Hind Limb ◽  
Sexual Size Dimorphism ◽  
Conservation Management ◽  
Head Width ◽  
Microhabitat Use ◽  
Grass Cover ◽  
Size Dimorphism ◽  
Conservation Implications ◽  
Putative Species ◽  
Effective Conservation

Abstract The Gongylomorphus skinks are an endemic genus of Mauritius and comprise two described species. Following the recent discovery of a third putative species, endemic to Flat Island, 11 km off the coast of Mauritius, this study was conducted to examine morphometrics and the pattern of microhabitat use by the species in an effort to provide effective conservation recommendations. There was a clear sexual size dimorphism with males significantly larger than females in terms of; snout-vent length, head length, head width, snout-mouth length, snout-ear length, upper and lower fore- and hind-limb lengths and fourth toe length. There was no sexual dimorphism in other measures including pelvic width, width at the base of the tail, head depth or body weight. Microhabitat use was found to be non-random with lizards occurring in areas with high humidity, high numbers of natural refugia, increased leaf litter coverage and plant species diversity, and low grass cover. We found no evidence that microhabitat use varied in relation to sex or age of lizards. The implications of these results for the conservation management of Flat Island for the orange-tail skink are discussed.

scholarly journals The influence of sample distribution on growth model output for a highly-exploited marine fish, the Gulf Corvina (Cynoscion othonopterus)

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5582 ◽  
Author(s):  
Derek G. Bolser ◽  
Arnaud Grüss ◽  
Mark A. Lopez ◽  
Erin M. Reed ◽  
Ismael Mascareñas-Osorio ◽  
...  
Keyword(s):  
Growth Model ◽  
Marine Fish ◽  
Growth Models ◽  
Growth Patterns ◽  
Von Bertalanffy ◽  
Model Output ◽  
Age Classes ◽  
Equal Distribution ◽  
Sample Distribution ◽  
Richards Model

Estimating the growth of fishes is critical to understanding their life history and conducting fisheries assessments. It is imperative to sufficiently sample each size and age class of fishes to construct models that accurately reflect biological growth patterns, but this may be a challenging endeavor for highly-exploited species in which older fish are rare. Here, we use the Gulf Corvina (Cynoscion othonopterus), a vulnerable marine fish that has been persistently overfished for two decades, as a model species to compare the performance of several growth models. We fit the von Bertalanffy, Gompertz, logistic, Schnute, and Schnute–Richards growth models to length-at-age data by nonlinear least squares regression and used simple indicators to reveal biased data and ensure our results were biologically feasible. We then explored the consequences of selecting a biased growth model with a per-recruit model that estimated female spawning-stock-biomass-per-recruit and yield-per-recruit. Based on statistics alone, we found that the Schnute–Richards model described our data best. However, it was evident that our data were biased by a bimodal distribution of samples and underrepresentation of large, old individuals, and we found the Schnute–Richards model output to be biologically implausible. By simulating an equal distribution of samples across all age classes, we found that sample distribution distinctly influenced model output for all growth models tested. Consequently, we determined that the growth pattern of the Gulf Corvina was best described by the von Bertalanffy growth model, which was the most robust to biased data, comparable across studies, and statistically comparable to the Schnute–Richards model. Growth model selection had important consequences for assessment, as the per-recruit model employing the Schnute–Richards model fit to raw data predicted the stock to be in a much healthier state than per-recruit models employing other growth models. Our results serve as a reminder of the importance of complete sampling of all size and age classes when possible and transparent identification of biased data when complete sampling is not possible.

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