Large Bodied Research Articles

Pattern and process in the distribution of North American freshwater fish

Published species lists were analysed to determine the contributions of dispersal, habitat preference, river channel size, body size, and glacial history to large-scale patterns in freshwater fish species richness in North America, north of central Mexico. Total species richness declines to the north and west but the pattern for endemics differs from that of widespread species. Mississippi Basin regions are more species rich than more isolated, coastal, regions. Richness declines more rapidly with increasing latitude in riverine specialist than in habitat generalist species. Levels of endemism are greatest in species found in small- to medium-sized river channels. The strong Rapoport effect, more marked in migratory than resident species, is correlated with habitat preference, channel size, and glacial history. Body size increases with latitude, largely as a result of a trend from small resident to large migrant species. In unglaciated regions, ancestral species survived in large habitats because these are longer-lived, more extensive, less isolated and more stable than headwaters, permitting larger populations and lower extinction levels. Reduced levels of gene flow in small, peripheral, channels isolated by larger downstream habitats have resulted in the production of many, small range, small-bodied species. The latitudinal richness gradient is a consequence of speciation and extinction events in unglaciated faunas and an increasing domination of faunas by generalist, large bodied, large channel, recolonizing species in more northern regions. (C) 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 46-61.

Inevitable evolution: back toThe Originand beyond the 20th Century paradigm of contingent evolution by historical natural selection

Since neo-Darwinism arose from the work of Darwin and Mendel evolution by natural selection has been seen as contingent and historical being defined by an a posteriori selection process with no a priori laws that explain why evolution on Earth has taken the direction of the major evolutionary trends and transitions instead of any other direction. Recently, however, major life-history trends and transitions have been explained as inevitable because of a deterministic selection that unfolds from the energetic state of the organism and the density-dependent competitive interactions that arise from self-replication in limited environments. I describe differences and similarities between the historical and deterministic selection processes, illustrate concepts using life-history models on large body masses and limited reproductive rates, review life-history evolution with a wider focus on major evolutionary transitions, and propose that biotic evolution is driven by a universal natural selection where the long-term evolution of fitness-related traits is determined mainly by deterministic selection, while contingency is important predominately for neutral traits. Given suitable environmental conditions, it is shown that selection by energetic state and density-dependent competitive interactions unfolds to higher level selection for life-history transitions from simple asexually reproducing self-replicators to large bodied organisms with senescence and sexual reproduction between males and females, and in some cases, to the fully evolved eusocial colony with thousands of offspring workers. This defines an evolutionary arrow of time for open thermodynamic systems with a constant inflow of energy, predicting similar routes for long-term evolution on similar planets.

Does divergence in female mate choice affect male size distributions in two cave fish populations?

Sexual selection by female choice can maintain male traits that are counter selected by natural selection. Alteration of the potential for sexual selection can thus lead to shifts in the expression of male traits. We investigated female mate choice for large male body size in a fish (Poecilia mexicana) that, besides surface streams, also inhabits two caves. All four populations investigated, exhibited an ancestral visual preference for large males. However, only one of the cave populations also expressed this female preference in darkness. Hence, the lack of expression of female preference in darkness in the other cave population leads to relaxation of sexual selection for large male body size. While P. mexicana populations with size-specific female mate choice are characterized by a pronounced male size variation, the absence of female choice in one cave coincides with the absence of large bodied males in that population. Our results suggest that population differences in the potential for sexual selection may affect male trait variation.

A review of Australian Cymadusa (Crustacea: Amphipoda: Ampithoidae) with descriptions of eight new species

Cymadusa is a large genus of large bodied, predominantly tropical ampithoid amphipods. Prior to this paper 22 species were recognised in Cymadusa of which four were known from Australia. Eight new species are described from Australia, increasing the known Australian species to 12. The new species described herein are: C. chuawe sp. nov. , C. elegantis sp. nov. , C. heronensis sp. nov. , C. jiigurru sp. nov. , C. pemptos sp. nov. , C. thagaay sp. nov. , C. tishana sp. nov. and C. wistari sp. nov. Ampithoe flindersi Stebbing, 1888 is synonymised with Cymdusa setosa (Haswell, 1879). Diagnoses and a key to the Australian species are provided.

Molecular phylogeny of pontobdelline leeches and their place in the descent of fish leeches (Hirudinea, Piscicolidae)

Phylogenetic relationships of all genera of the fish leech subfamily Pontobdellinae were investigated using mitochondrial (12S rDNA, COI, tRNA‐Leu, ND1) and nuclear (28S rDNA) DNA sequences under maximum likelihood, Bayesian inference and parsimony. All methods resulted in trees that corroborated the monophyly of the family Piscicolidae, but recovered their subfamily Pontobdellinae as non‐monophyletic. Based on the basal position of the giant Antarctic Megaliobdella szidati, it is hypothesized that the putative ancestor of fish leeches was a free‐ranging, large bodied, muscular leech. The next branch contains parasites of cartilaginous fishes, Pontobdella muricata and Pontobdella macrothela. Two remaining genera of the subfamily (the Arctic Oxytonostoma and the Antarctic Moorebdellina) showed weak affinities to other piscicolid taxa. The obtained phylogenetic hypothesis suggests a possible transition from an ancestral free‐ranging life style and temporary parasitism, to parasitism on cartilaginous fishes, followed by parasitism on bony fishes.

Differences in Population Growth and Morphometric Characteristics of Three Strains of Brachionus angularis

ABSTRACT Three strains of the rotifer Brachionus angularis Gosse collected respectively from localities near Qingdao, Guangzhou, and Wuhu cities were cultured at 25±1°C to compare their population growth and morphometric characteristics when their were fed different algal foods (Chlorella pyrenoidosa, Scenedesmus obliquus, or a 1:1 mixture of both algae). The population growth rate, body size, egg size, and relative egg size were all significantly affected by food type. Among the three types of food, the rotifers fed C. pyrenoidosa had the lowest population growth rate. Rotifers fed S. obliquus had larger body size and egg size than those fed C. pyrenoidosa. Among the three rotifer strains, the population growth rate and the body size of Wuhu strain was the lowest and largest, respectively, and the ratio of body width to body length of Wuhu strain was the smallest. There were significant relationships between body size and egg size in all three strains. With all three strains, larger bodied rotifers tended to produce larger clutches of eggs, and, except for the Qingdao strain, there was a positive correlation between clutch size and egg size. Eggs of the Qingdao strain were the largest at clutch size 3.

Life-history diversification in the Middle Danubian fish fauna - a conservation perspective

I evaluated the diversity of the life-history attributes of Middle Danubian fish species in relation to a trilateral life-history continuum model. Life-history strategies could be characterized for 70 species. Multivariate analysis identified a gradient in life-history variables from species having larger body size, delayed maturation, longer life span, larger fecundity and no marked parental care to species with the opposite suite of traits. A second gradient further delineated species based predominantly on egg size and the development of parental care. Diversity of life-history strategies tended to increase from headwater to large river habitats. A comparison of life-history attributes between native and exotic fishes showed that exotic species modify the general life-history diversification of the native fauna. Exotic species were rather small, performed relatively well developed parental care and laid a small number of large eggs (i.e. they displayed intermediate-equilibrium strategist features). Temporal changes in the patterns of life-history diversification (i.e. the rarity or disappearance of large bodied, highly fecund species with late maturation (i.e. periodic strategist sturgeons), and the invasion of the intermediate-equilibrium strategist exotic species) could be well associated with the alteration of the Middle Danubian hydrosystem. The present study supports the prediction that life-history variables can be useful in the monitoring and conservation management of running water habitats.

Developmental dynamics of some blood biochemical parameters in the growing turkey (Meleagris gallopavo)

Blood serum clinical biochemical parameters of fasted BUT Big 8 male turkeys were determined at the ages of 3 days, 4, 8, 12, 16 and 20 weeks, for a follow-up of the developmental changes of some serum metabolites, enzymes and ions. The serum protein content (total protein, albumin, globulin) increased with age, indicating also the moulting-associated metabolic changes in the age interval from the 8th to the 12th weeks. Creatinine was shown to have a peak at 3 days of age (role of muscle activity in thermogenesis), while urate concentration sensitively reflected the dietary protein amount. Serum triglycerides peaked at the time of yolk catabolism, while cholesterol was shown to indicate the moulting, as was serum malondialdehyde. Serum sodium content increased throughout the study. Alanine aminotransferase and aspartate aminotransferase activities increased along the ontogeny, while alkaline phosphatase activity decreased in parallel with the growth. Serum creatine kinase activity showed an over one-magnitude increase. General metabolic and enzymatic alterations were characteristic and applicable for the description of the ontogenetic development of a precocial (post-hatch triglyceride peak), large bodied, meat-type (lactate dehydrogenase, continuously increasing creatine kinase) bird species.

Should we expect large game specialization in the late Pleistocene? An optimal foraging perspective on early Paleoindian prey choice

Several recent studies employ foraging theory to model early Paleoindians as big game specialists who focused on hunting large bodied, high-return animals such as mammoths. In this paper, we evaluate the specialist model by identifying the range of handling times and encounter rates within which mammoth ( Mammuthus columbi) specialization would occur. We continue by using allometric relationships between body size and population density in mammals to estimate encounter rates for mammoth and other North American species. Combining these two pieces of information allows for the construction of an optimal diet curve representative of late Pleistocene prey choice, given the inclusion of mammoth. Our results seriously question the model of early Paleoindians as megafaunal specialists and suggest that foragers should have pursued a wide array of taxa including not only mammoth, but the full range of ungulates and some smaller game as well. These results accord well with empirical data on prey choice from late Pleistocene archaeological contexts from across North America.

Stability with Inheritance in the Conditional Strategy

The conditional strategy is a theoretical framework that explains the existence within populations of individuals that express alternative behavioral, physical or life history tactics (phenotypes). An example is fighters and sneakers in many animal mating systems. In the conditional strategy the alternative tactics are chosen by individuals based on their state, for example large or small bodied. Since state is often heritable, due for example to additive genetic variance, the alternative tactics may also have inheritance. As the tactics do not have equal fitnesses, it is generally believed that any such inheritance would prevent the evolutionary stability of the conditional strategy. However, in previous work we introduced an Inheritance Theorem and were able to prove that a conditional strategy with tactic inheritances can have a unique equilibrium proportion of the tactics. We now prove a second property of our Inheritance Theorem, namely the stability of the equilibrium. This means that if the tactics are perturbed from their equilibrium proportions, they will return across generations to their equilibrium proportions. An example is provided in mites. We have therefore established an Inheritance Theorem which includes both the existence of an equilibrium and its stability for alternative tactics in a conditional strategy.

The Adaptive Zone of the Genus Gerygone (Acanthizidae) as Shown by Morphology and Feeding Habits

SummaryUsing body morphology, feeding ecology and behaviour, this paper describes the adaptive zone of the species-rich Australo-Pacific genus Gerygone. Gerygone is a genus of small bodied, specialist insectivores that obtain the majority of their prey by gleaning and snatching it from the foliage. Species tend to be ecologically and morphologically similar. Evolution has mainly taken the form of specialisation to different habitats, to produce a largely allopatric assemblage of species. In this it parallels the larger bodied, foliage-gleaning Lichenostomus honeyeaters and contrasts with other species-rich endemic warbler-like genera, such as Sericornis and Acanthiza, where sympatric species exploit different substrates, forage at different heights above the ground, and use different foraging behaviours. The greatest evolutionary shifts occur in the insular species, Gerygone igata and G. albofrontata, which are morphologically and ecologically distinct from other Gerygone. On the limited data available, it appears that the morphological radiation of Gerygone in Australia and New Guinea is constrained by the abundance of other insectivorous genera.

Multiple Trophic Level Structuring in Salvelinus–Coregonus Assemblages in Boreal Forest Lakes

Hypolimnetic trophic interactions were examined among lake trout (Salvelinus namaycush), cisco (Coregonus artedi), zooplankton, and macroinvertebrates in six northwestern Ontario lakes varying sevenfold in conductivity. Faster growth and larger body size of lake trout in high-conductivity lakes were associated with larger meal sizes, earlier entry of cisco into their diet, and consumption of relatively few, large-bodied prey. Cisco preyed on zooplankton and macroinvertebrates. Cisco were abundant, large bodied, and fast growing in high-conductivity lakes. In one low-conductivity lake (Greenwich Lake), lake trout were 12 times as abundant as cisco whereas in all other lakes, lake trout to cisco ratios were ~ 1:1 or less regardless of conductivity. In Greenwich Lake, lake trout consumed large quantities of age-0 cisco and Mysis relicta, which was associated with "top-down" trophic structuring. Food web analyses strongly suggest that in Greenwich Lake the high abundance of piscivores resulted directly in a low abundance of planktivores and indirectly in a large-bodied zooplankton community and planktivores with rapid growth rates.

Avian Community Dynamics in Desert Grasslands: Observational Scale and Hierarchial Structure

Avian communities living in a complex environment were studied by censuses of singing males, using several levels of resolution which focussed on different properties of the community. Within each level of resolution, various community parameters in two grassland habitat types were calculated over the entire breeding season, and for census intervals within the breeding season. The community level of resolution focussed on community—wide patterns, such as total density and total biomass, in order to reveal constraints operating on all species in each habitat. An intermediate level of resolution focussed on relative properties of species such as relative abundances, species richness, and dominance concentration. At the individual species level of resolution, densities and identities of species were the properties upon which the analysis focussed. These techniques allowed characterization of responses of the avian communities to complex changes in the system in which they were embedded. Long—term averages in monthly rainfall on the sites used for this study indicated a bimodal distribution of rainfall. The first peak occurred in December and the second in July and August. During the two years of study, summer rainfall was similar, but winter rainfall in 1983 was °2—3 times as great as in 1982. Avian communities in habitats with mesquite trees (mesquite savannah) responded differently than communities in grassland habitats, and these responses could be seen at different levels of resolution. Peak densities and biomass occurred during May—June in mesquite savannah habitats, while grassland communities achieved highest densities and biomass during July and August. Average density per individual showed little seasonal pattern, but was lower for mesquite savannah communities than for grassland communities. Species richness increased in mesquite savannah habitats in 1983, but decreased in grassland habitats that year. Patterns of evenness and dominance concentration suggested that in 1983, rare species of large body size were added to the community in mesquite savannah, while in grassland habitats, species already present during 1982 increased in density. A community ordination revealed that mesquite savannah habitats were dominated numerically by small—bodied insectivorous species during the early part of the breeding season but became similar to grassland communities in July and August. Grassland communities were dominated by large—bodied emberizine finches. These characteristics of the avian communities corresponded closely to the phenology of important primary producers. Mesquite produces leaves high in nutritional value and produces flowers during April—June; thereafter older leaves decline in nutrient content and flowers disappear. These changes in mesquite productivity undoubtedly produce corresponding changes in insect communities exploitable by small—bodied insectivores. Perennial grasses concentrate aboveground productivity to July—August and insect communities associated with grasses increased in biomass during this period, thus increasing resources available for breeding. These results suggest that avian community responses to complex changes in their environments can be identified and related to outside inputs into the environment, such as rainfall. Identification of community responses is facilitated by emphasis on several observational scales. Communities appear individualistic to observers because (1) adaptational units of species are probably much larger than study areas; (2) species ability to adapt to local conditions might be diluted by gene flow among populations; and (3) if most evolutionary change occurs during speciation, then species adaptations will reflect a relatively narrow range of selection pressures that operated briefly on the species during the past.

Transient kinetics of the rapid shape change of unstirred human blood platelets stimulated with ADP.

Unstirred (isotropic) suspensions of human blood platelets stimulated with ADP in a stopped-flow laser turbidimeter exhibit a distinct extinction maximum during the course of the classical rapid conversion of initially smooth flat discoid cells to smaller-body spiny spheres. This implies the existence of a transient intermediate having a larger average light scattering cross section (extinction coefficient) than either the disc or the spiny sphere. Monophasic extinction increases reaching the same final value were observed when either discoid or spiny sphere platelets were converted to smooth spheres by treatment with chlorpromazine, and sphering of discoid cells was accompanied by a larger total extinction change than the retraction of pseudopods by already spherical cells. These and other results suggest that the ADP-induced transient state represents platelets that are approximately as "spherical" as the irregular spiny sphere but lack the characteristic long pseudopods and as a consequence are larger bodied. Fitting the ADP progress curves to the series reaction A leads to B leads to C by means of the light scattering equivalent of the Beer-Lambert law yielded scattering cross sections that are consistent with this explanation. The rate constants for the two reaction steps were identical, indicating that ADP activation corresponds to a continuous random (Poisson) process with successive apparent states "disc," "sphere," and "spiny sphere," whose individual probabilities are determined by a single rate-limiting step.

Locomotory mechanisms in Antarctic pycnogonids

Patterns of walking, modes of joint movement, and individual limb diversity were analysed with the aid of cine film of several living Antarctic pycnogonids, including the 8-legged Colossendeis australis, C. angusta, Pallenopsis patagonica, and Nymphon sp., the 10-legged Decolopoda australis, and the 12-legged Dodecolopoda mawsoni. Appendage musculature of several of these species and also of the 10-legged Pentapycnon charcoti and Pentanymphon antarcticurn was dissected. At least two distinct morphotypes were identified: a short-legged, crawling variety (P. charcoti); and the more typical long-legged, large bodied, walking forms. No gross differences in musculature of joints were noted in the species examined. All joints are, at least superficially, hinge joints. The coxa-body joint is largely immobile, the coxa 1-coxa 2 joint alone exhibits promotion-remotion and all other joints are flexion-extension joints. The 8-legged forms move in an imprecise manner, there being irregularity of leg raising and lowering and where legs touch down in relation to the body and to other legs. The 10- and 12-legged forms exhibit more precise patterns of metachronal leg movements. Although legs move in a basic promotion-remotion, extension-flexion mode, there is a certain degree of twisting of a leg as it is picked up, brought forward, and set down; models indicating how such joint movement occurs were constructed. The possibility that hydrostatic pressure is employed in extension is considered and is found to be remote. Lateral placement of legs, orientated in almost all directions in the horizontal plane of the trunk, achieves a versatility of movement similar to that in crabs. Comments on pycnogonid taxonomic affinities are offered.

Ovarian Follicular Development in Egg and Growth Lines of Japanese Quail

Ovarian follicular development in a line of quail selected for 14 generations for increased 4-week body weight (mean female mature body weight of about 220 g.) was compared to a control line (mean female mature body weight of about 138 g.). Egg weight and yolk weight were greater in the larger bodied (P line) than in the smaller (C line) birds. Follicular rapid development and rest period were of longer duration in the P line than in the C line in young birds but not in older ones. Significant correlations were noted between yolk weight and egg weight (.88 and .87), and yolk weight and the duration of rapid development (.62 and .47) in both young and older birds, respectively. A correlation of .39 (P<.05) was noted between the duration of rapid development and egg weight in the younger birds only.