scholarly journals Body size and extinction risk in Brazilian carnivores

2009 ◽  
Vol 9 (2) ◽  
pp. 45-49 ◽  
Author(s):  
German Forero-Medina ◽  
Marcus Vinícius Vieira ◽  
Carlos Eduardo de Viveiros Grelle ◽  
Paulo Jose Almeida
Keyword(s):  
Body Size ◽  
Litter Size ◽  
Life Histories ◽  
Linear Models ◽  
Extinction Risk ◽  
Habitat Destruction ◽  
Phylogenetically Independent Contrasts ◽  
Relationship Of ◽  
The Relationship ◽  
Natural Reserves

Because extinctions are not random across taxa, it is important for conservation biologists to identify the traits that make some species more vulnerable. Factors associated with vulnerability include small geographical ranges, low densities, high trophic level, "slow" life histories, body size, and tolerance to altered habitats. In this study we examined the relationship of body size, reproductive output, longevity, and extinction risk for carnivores occurring in Brazil. We used generalized linear models analyses on phylogenetically independent contrasts to test the effect of body size alone, and the combined effect of body size, litter size and longevity on extinction risk. Body size appeared in the two best models according to the selection criteria (AIC), and it was the most plausible bionomic variable associated with extinction risk. Litter size and longevity, bionomic traits previously associated with threat risk of Brazilian carnivores, were implausible. The higher extinction risk for larger species could result from body size influencing vulnerability to different human activities, such as killing, habitat destruction and fragmentation, and the small size of natural reserves.

scholarly journals Age-related decline in executive function as a hallmark of cognitive ageing in primates: an overview of cognitive and neurobiological studies

2020 ◽  
Vol 375 (1811) ◽  
pp. 20190618 ◽  
Author(s):  
Agnès Lacreuse ◽  
Naftali Raz ◽  
Daniel Schmidtke ◽  
William D. Hopkins ◽  
James G. Herndon
Keyword(s):  
Executive Function ◽  
Age Differences ◽  
Cognitive Processes ◽  
Life Histories ◽  
Primate Species ◽  
Cognitive Ageing ◽  
Age Related ◽  
Relationship Of ◽  
The Relationship ◽  
Ageing Brain

Executive function (EF) is a complex construct that reflects multiple higher-order cognitive processes such as planning, updating, inhibiting and set-shifting. Decline in these functions is a hallmark of cognitive ageing in humans, and age differences and changes in EF correlate with age-related differences and changes in association cortices, particularly the prefrontal areas. Here, we review evidence for age-related decline in EF and associated neurobiological changes in prosimians, New World and Old World monkeys, apes and humans. While EF declines with age in all primate species studied, the relationship of this decline with age-related alterations in the prefrontal cortex remains unclear, owing to the scarcity of neurobiological studies focusing on the ageing brain in most primate species. In addition, the influence of sex, vascular and metabolic risk, and hormonal status has rarely been considered. We outline several methodological limitations and challenges with the goal of producing a comprehensive integration of cognitive and neurobiological data across species and elucidating how ageing shapes neurocognitive trajectories in primates with different life histories, lifespans and brain architectures. Such comparative investigations are critical for fostering translational research and understanding healthy and pathological ageing in our own species. This article is part of the theme issue ‘Evolution of the primate ageing process’.

Carcass additions increase juvenile salmonid growth, condition, and size in an interior Columbia River Basin tributary

2020 ◽  
Vol 77 (4) ◽  
pp. 703-715 ◽  
Author(s):  
Matthew J. Kaylor ◽  
Seth M. White ◽  
Edwin R. Sedell ◽  
Dana R. Warren
Keyword(s):  
Body Size ◽  
Growth Rates ◽  
Life Histories ◽  
Freshwater Ecosystems ◽  
Steelhead Trout ◽  
Juvenile Salmonids ◽  
Early Fall ◽  
Juvenile Chinook ◽  
The Relationship

Numbers of anadromous fish returning to freshwater ecosystems have declined precipitously across much of western North America, reducing a potentially important resource subsidy for juvenile salmonids. We added carcasses to three sections of a Snake River tributary and assessed juvenile Chinook salmon (Oncorhynchus tshawytcha) and steelhead trout (Oncorhynchus mykiss) growth, body condition, size, and diet responses in summer and early fall. Juvenile salmonids consumed an abundance of eggs and carcass tissue, which increased energy rations. Within 3 weeks of carcass additions, juvenile Chinook and steelhead growth rates were 1.1–5 and 6–23 times greater in treatment reaches relative to control reaches, respectively. We used long-term tagging and detection data from this system to assess the relationship between juvenile Chinook size and emigration survival for two different juvenile life histories. The increased growth rates and body size in response to carcass additions, coupled with a positive relationship between body size and survival, suggest that juvenile salmonid rearing productivity and emigration survival may be limited by depressed returns of anadromous fishes in this system and potentially other tributaries of the Columbia Basin.

The relationship of body size to survivorship of hatchling snapping turtles ( Chelydra serpentina ): an evaluation of the "bigger is better" hypothesis

Oecologia ◽  
1999 ◽  
Vol 121 (2) ◽  
pp. 224-235 ◽  
Author(s):  
Justin D. Congdon ◽  
Roy D. Nagle ◽  
Chirstopher W. Beck ◽  
Owen M. Kinney ◽  
S. Rebecca Yeomans ◽  
...  
Keyword(s):  
Body Size ◽  
Chelydra Serpentina ◽  
Snapping Turtles ◽  
Relationship Of ◽  
The Relationship

Biological Model of Fisheries Production Based on Physiological and Ecological Scalings of Body Size

1989 ◽  
Vol 46 (4) ◽  
pp. 614-623 ◽  
Author(s):  
P. R. Boudreau ◽  
L. M. Dickie
Keyword(s):  
Body Size ◽  
Individual Species ◽  
Data Series ◽  
Biomass Density ◽  
Fish Stocks ◽  
Population Sampling ◽  
Functional Relationships ◽  
Relationship Of ◽  
The Relationship ◽  
Population Equilibrium

Earlier ecological studies showing regularity in the relationship of certain indices of production to body size are used to develop a predictive equation of fish production on a year to year basis, with biomass and body size as independent stock variables. The prediction system makes use of the observed regular adjustments of local biomass density with body size and the parallelism of the functional relationships of production and biomass with body size both between and within stock cohorts. The method obviates the need to invoke assumptions of population equilibrium. The model is applied to three data series for individual species exploited by commercial fisheries on the Scotian Shelf. The results suggest that despite the vagaries of population sampling, ecological information can provide practical estimates of the production potential of fish stocks.

3.—The Cytology of the Parthenogenetic Australian Weevil Listroderes costirostris Schönh

1973 ◽  
Vol 69 (3) ◽  
pp. 71-89 ◽  
Author(s):  
Ann R. Sanderson
Keyword(s):  
Body Size ◽  
Chromosome Number ◽  
Polar Nucleus ◽  
Low Fertility ◽  
Arrested Development ◽  
Relationship Of ◽  
Bouquet Stage ◽  
The Relationship

SynopsisKaryograms prepared from ovarian and blastoderm cells of the parthenogenetic Australian Brown Vegetable Weevil demonstrate a consistent triploid condition with 30 chromosomes which can be grouped into 10 sets of homologues. Meiosis is replaced by a single mitotic-like division in which 30 univalent chromosomes, each composed of two chromatids, divide equationally between an ootid nucleus and a single polar nucleus. Prior to the differentiation of the oocytes a peculiar bouquet stage occurs in the cells of the end chamber of each ovariole, but the significance of this phase is not known. Arrested development in eggs from individuals of low fertility is investigated and the relationship of body size and chromosome number is discussed.

scholarly journals Species Abundance and Body Size Relationship of Bird Assemblages at Selected Sites in Western Sarawak

2020 ◽  
Vol 3 (2) ◽  
pp. a18-25
Author(s):  
AHMAD FITRI AZIZ ◽  
CHARLIE JUSTIN MERGIE LAMAN
Keyword(s):  
Body Size ◽  
Regression Line ◽  
Species Abundance ◽  
General Rule ◽  
Bird Assemblages ◽  
Energy Equivalence ◽  
Average Body Mass ◽  
Relationship Of ◽  
The Relationship ◽  
Combined Data

The Energy Equivalence Rule (EER) is an unresolved issue in ecology. This rule states that the amount of energy used for each species in a population is independent of its body size. A study on the relationship between abundance and body size of bird assemblages was conducted in Western Sarawak. Abundance data of bird assemblages from seven selected sites in Western Sarawak were used to produce a regression line of log absolute species abundance versus log average body mass. Data from all selected sites were combined to represent bird assemblages in Western Sarawak and the slope produced was -0.216. The slopes obtained for each site were 0.808, -0.080, -0.258, -0.067, -0.161, -0.072 and -0.237, respectively. Statistical analysis shows that the slope of combined data did not differ significantly from -0.75, as expected under the EER. Thus, this study shows that the EER can be applied as a general rule of community structure of bird assemblages in Western Sarawak.

scholarly journals ISOMETRY OF EGG SIZE IN A TEXAS POPULATION OF THE TURTLE STERNOTHERUS ODORATUS THAT EXHIBITS A NEARLY FIXED CLUTCH SIZE

2020 ◽  
pp. 13-17
Author(s):  
Peter V. Lindeman
Keyword(s):  
Body Size ◽  
Clutch Size ◽  
Egg Size ◽  
Female Body Size ◽  
Competing Demands ◽  
Sternotherus Odoratus ◽  
Central Texas ◽  
Relationship Of ◽  
The Relationship ◽  
Anatomical Constraints

In evaluating optimal egg-size theory and the effects of anatomical constraints on egg size in turtles, pivotal questions concern the significance of the relationship of egg size to female body size and whether the relationship is isometric or hypoallometric. In a central Texas population of the kinosternid turtle Sternotherus odoratus in which clutch size of a sample of turtles was nearly fixed (seven of eight females had two eggs while the largest female had three eggs), there was an isometric increase in egg width with body size among the females with two-egg clutches and significantly reduced egg width in the largest female’s three-egg clutch. Allometric analyses of populations that exhibit little variation in clutch size, as well as analysis of modal clutch sizes in populations with more variable clutch sizes, both have the potential to further illuminate the competing demands of increasing egg size vs. increasing clutch size as females grow larger, enabling them to optimize their reproductive output as it increases with body size.

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