Animal Life History Research Articles

SALTY SURVIVORS

Edited by Th. J. Abatzopoulos, J. A. Beardmore, J. S. Clegg and P. Sorgeloos Kluwer Academic Publishers (2002) pp. 286. ISBN 1402007469 (hbk) $113 (hbk) ![Figure][1] The power of brine shrimp ( Artemia sp.) to survive and even thrive in forbidding environments has long

The brine shrimp Artemia (Crustacea; Anostraca): a model organism to evaluate management policies in aquatic resources

Some organisms not only play an essential roleas models for scientific development, but alsohelp to bridge the gap between science andwhat society expects from it when some aspectof such organisms has an immediate applicationto satisfy evident human needs. The brineshrimp Artemia is a paradigmatic model in thisregard. The striking biological characteristicsof this organism have been successfully appliedto the development of marine fish andcrustacean farming (Lavens & Sorgeloos 2000).Artemia exhibits a unique ability to live andreproduce in waters of high salinity (0.4-3.4 M)and variable ionic conditions. Not surprisingly,members of the genus are referred as theextremophiles of the biological world, e.g., theencysted gastrula embryo (cyst) is the mostresistant of all animal life history stages, whilethe motile stages (nauplii and adults) areamong the best osmoregulators in the animalkingdom (Clegg & Trotman 2002). These andother amazing life history traits, including aneasy handling under laboratory conditions (DeLos Rios 2001), makes Artemia a modelorganism of choice for many basic disciplines,particularly for studies on adaptation andspeciation (Gajardo et al. 2002).As any exploited organism, Artemia oftenconfronts the interests of users and thoseseeking to protect the environment and localgenetic resources (Gajardo & Beardmore2001). Chile is potentially not an exception,and the objective of this letter is to draw theattention on the importance to protect localArtemia resources and their habitat.Hypersaline environments are ancient andvery unique ecological settings, distributed,though not exclusively, in tropical andsubtropical areas. The salty lakes and lagoonsscattered over the Salar de Atacama areconsidered quite unique since they exhibit acombination of biotic and abiotic conditionsthat have caused complex speciation patterns inArtemia (Gajardo et al. 1998, 2002).Accordingly, some local Artemia populationsare genetically unique in relation to regional orglobal biodiversity. Two out of seven bisexualArtemia species are found in Chile, namely A.franciscana (Kellog 1906) and A. persimilis(Piccinelli & Prosdocini 1968). The former, thedominant species in the Americas, isdistributed in north and central Chile, between18-30o S (Gajardo et al. 1998). Geneticanalyses at different levels (e.g., DNA, protein-coding loci and karyological traits) (Gajardo B cystdiameter and naupliar size).Both the autochthonous Artemia and theirhabitat can be threatened by ongoing miningactivities in “salares” of the Atacama desert,which are rich mineral deposits. But foreseenrisks are likely to come as marine fish farming,which typically uses Artemia nauplii as live foodfor fish larval stages, continuous to growworldwide, including Chile. A significantproportion of Artemia cysts traded in worldmarkets used to be harvested from Great SaltLake (GSL) in Utah, USA. However, harvestunpredictability and cyst shortage (less than 2,500tons are from GSL) has urged producers toexplore new sites around the world. LocalArtemia resources in Chile might be of highpriority, provided they meet international qualitystandards and turn out more cost-effective inrelation to what the world market offers.Harvesting pressure on sites in Chile couldselectively deplete certain genotypes, whilsttranslocation or introduction of new and exoticspecies or populations (e.g., parthenogenetictypes) that can out compete local ones, could

Productivity, trophic structure, and energy flow in the steady-state ecosystems of Silver Springs, Florida

Animals originated in the oceans and evolved there for hundreds of millions of years before adapting to terrestrial environments. Today, oceans cover more than two-thirds of Earth and generate as much primary production as land. The path from the first macrobiota to modern marine biodiversity involved parallel increases in terrestrial nutrient input, marine primary production, species’ abundance, metabolic rates, ecotypic diversity and taxonomic diversity. Bottom-up theories of ecosystem cascades arrange these changes in a causal sequence. At the base of marine food webs, nutrient fluxes and atmosphere–ocean chemistry interact with phytoplankton to regulate production. First-order consumers (e.g., zooplankton) might propagate changes in quantity and quality of phytoplankton to changes in abundance and diversity of larger predators (e.g., nekton). However, many uncertainties remain about the mechanisms and effect size of bottom-up control, particularly in oceans across the entire history of animal life. Here, we review modern and fossil evidence for hypothesized bottom-up pathways, and we assess the ramifications of these processes for four key intervals in marine ecosystems: the Ediacaran–Cambrian (635–485 million years ago), the Ordovician (485–444 million years ago), the Devonian (419–359 million years ago) and the Mesozoic (252–66 million years ago). We advocate for a clear articulation of bottom-up hypotheses to better understand causal relationships and proposed effects, combined with additional ecological experiments, paleontological documentation, isotope geochemistry and geophysical reconstructions. How small-scale ecological change transitions into large-scale evolutionary change remains an outstanding question for empirical and theoretical research.

Effects of increased atmospheric CO2 on sea urchin early development

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 274:161-169 (2004) - doi:10.3354/meps274161 Effects of increased atmospheric CO2 on sea urchin early development H. Kurihara*, Y. Shirayama Seto Marine Biological Laboratory, Kyoto University, 459 Shirahama, Nishimuro, Wakayama, 649-2211, Japan *Email: harukoku@e-mail.jp ABSTRACT: Increased carbon dioxide (CO2) concentration in the atmosphere will change the balance of the components of carbonate chemistry and reduce the pH at the ocean surface. Here, we report the effects of increased CO2 concentration on the early development of the sea urchins Hemicentrotus pulcherrimus and Echinometra mathaei. We examined the fertilization, early cleavage, and pluteus larval stage to evaluate the impact of elevated CO2 concentration on fertilization rate, cleavage rate, developmental speed, and pluteus larval morphology. Furthermore, we compared the effects of CO2 and HCl at the same pH in an attempt to elucidate any differences between the two. We found that fertilization rate, cleavage rate, developmental speed, and pluteus larval size all tended to decrease with increasing CO2 concentration. Furthermore, CO2-seawater had a more severe effect than HCl-seawater on the fertilization rate. By contrast, the effects on cleavage rate, developmental speed, and pluteus larval morphology were similar for CO2- and HCl-seawater. Our results suggest that both decreased pH and altered carbonate chemistry affect the early development and life history of marine animals, implying that increased seawater CO2 concentration will seriously alter marine ecosystems. The effects of CO2 itself on marine organisms therefore requires further clarification. KEY WORDS: CO2 · pH · Sea urchin · Early development · Biological impact · Global change Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 274. Online publication date: June 24, 2004 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2004 Inter-Research.

Prolonged diapause and the stability of host–parasitoid interactions

We investigated the effect on host–parasitoid dynamics of prolonged diapause, a feature of the life history of many animals living in unpredictable environments, by modifying the classical May (J. Anim. Ecol. 47 (1978) 833) host–parasitoid model. We considered three patterns of development of host and parasitoid: (a) prolonged parasitoid diapause controlled by host physiology, (b) parasitoid interference in host development, preventing parasitized hosts from prolonging diapause, and (c) host diapause independent of parasitoid attack. We found that single-year prolonged diapause shifted the boundaries of the May model towards a slight increase in stability. Longer periods of diapause prolongation had a stronger influence, but this influence remained modest if we considered realistic parameter values. In contrast to other recent studies, our results suggest that prolonged diapause does not necessarily compensate for the destabilizing effects of time lags on the influence of parasitoids on population dynamics.

Diel vertical migration of zooplankton following optimal food intake under predation

A model is developed to investigate the trade-offs between benefits and costs involved in zooplanktonic diel vertical migration (DVM) strategies. The 'venturous revenue' (VR) is used as the criterion for optimal trade-offs. It is a function of environmental factors and the age of zooplankter. During vertical migration, animals are assumed to check instantaneously the variations of environmental parameters and thereby select the optimal behavioral strategy to maximize the value of VR, i.e. taking up as much food as possible with a certain risk of mortality. The model is run on a diel time scale (24 h) in four possible scenarios during the animal's life history. The results show that zooplankton can perform normal DVM balancing optimal food intake against predation risk, with the profile of DVM largely modified by the age of zooplankter.

RESPONSE OF LARVAL RELEASE OF UCA TO TIDE IN THE YOSHINO RIVER MOUTH

The intertidal flat at the mouth of the Yoshino River is well-known as one of few remaining habitatsfor fiddler crabs, Genus Uca, that are classified in the near threatened species in the Red Data List edited by the Environmental Agency of Japan. To understand characteristics of this benthic animal's life history on and around the intertidal flat is useful for examining conservation methods of thearea. In this study, the hatching and dispersion process of the larvae of Genus Uca were investigated through laboratory experiments and field observations. The results are summarized as follows: 1) The larvae of Genus Uca are hatched during a restricted period around a flood tide in a spring tide. 2) The adaptability of zoeae to variations of salinity is considered to be fairly high because they were collected at positions with a wide rangc of salinity. 3) The amount of zoeaindividuals emerging in one hour at this intertidal flat was estimated to be about 150, 000.

Parasites in Hosts with Special Life Histories

One-hundred and forty seven specimens of the Cuckoo Cuculus canorus, 356 individuals of the Crossbill Loxia curvirostra and 79 specimens of the Swift Apus apus were captured on the Curonian Spit in the Baltic Sea and investigated for haematozoa by microscopic examination of stained blood smears. Haemosporidian parasites (Sporozoa, Haemosporida) were not recorded in the Cuckoo and the Swift. However, in juvenile Crossbills the prevalence of Haemoproteus tartakovskyi (9.0%), H. fringillae (2.8%), Leucocytozoon fringillinarum (15.5%), L. dubreuili (5.1%) and L. majoris (3.9%) was recorded. Special life histories protect birds from getting infected with haemosporidian parasites either completely or at least during the first months of their life when they are especially vulnerable to parasitic infections. Hence this advantage is likely to have contributed to the evolution of special animal life histories. Parasites in hosts with special life histories provide excellent natural, experiments, enabling to solve some intricate puzzles of ecological parasitology by relatively simple and inexpensive methods.

Estimating stature in fossil hominids: which regression model and reference sample to use?

Researchers have long appreciated the significant relationship between body size and an animal's overall adaptive strategy and life history. However, much more emphasis has been placed on interpreting body size than on the actual calculation of it. One measure of size that is especially important for human evolutionary studies is stature. Despite a long history of investigation, stature estimation remains plagued by two methodological problems: (1) the choice of the statistical estimator, and (2) the choice of the reference population from which to derive the parameters.This work addresses both of these problems in estimating stature for fossil hominids, with special reference to A.L. 288-1 (Australopithecus afarensis) and WT 15000 (Homo erectus). Three reference samples of known stature with maximum humerus and femur lengths are used in this study: a large (n=2209) human sample from North America, a smaller sample of modern human pygmies (n=19) from Africa, and a sample of wild-collected African great apes (n=85). Five regression techniques are used to estimate stature in the fossil hominids using both univariate and multivariate parameters derived from the reference samples: classical calibration, inverse calibration, major axis, reduced major axis and the zero-intercept ratio model. We also explore a new diagnostic to test extrapolation and allometric differences with multivariate data, and we calculate 95% confidence intervals to examine the range of variation in estimates for A.L. 288-1, WT 15000 and the new Bouri hominid (Australopithecus garhi).Results frequently vary depending on whether the data are univariate or multivariate. Unique limb proportions and fragmented remains complicate the choice of estimator. We are usually left in the end with the classical calibrator as the best choice. It is the maximum likelihood estimator that performs best overall, especially in scenarios where extrapolation occurs away from the mean of the reference sample. The new diagnostic appears to be a quick and efficient way to determine at the outset whether extrapolation exists in size and/or shape of the long bones between the reference sample and the target specimen.

Adaptive Significance of a Small Heat Shock/α-Crystallin Protein (p26) in Encysted Embryos of the Brine Shrimp,Artemia franciscana

Encysted embryos of the primitive crustacean, Artemia franciscana, are among the most resistant of all animal life history stages to extremes of environmental stress. This resistance has likely been acquired during evolutionary adaptation to their harsh ecological setting. In the laboratory, for example, some of these embryos survive more than 6 years of continuous anoxia while fully hydrated and at room temperature, a phenomenal capability that can easily be related to their frequent encounters with anoxic conditions in nature. A small heat shock protein belonging to the α-crystallin family of proteins, referred to as p26, appears to play a central role in the stress resistance of these embryos. Our evidence shows that this protein is an important component in their adaptive repertoire, and vital for the survival of Artemia in nature.

Apparent Heritability of Parental Care in Savannah Sparrows

Parental effort measures the total amount of time and energy allocated toward care of offspring, and it is often an obvious and variable component of an animal's life history (Winkler and Wilkinson 1988, Clutton-Brock 1991). Among birds, intraspecific variation in parental effort is more quantitative than qualitative. Individual adults differ in feeding rate (Yasukawa et al. 1990, Wright and Cuthill 1992), intensity of offspring defense (Winkler 1992), and tendency to engage in prolonged associations with young (Weatherhead and McRae 1990). Like all quantitative traits, intraspecific variation in parental effort can be attributed to genetic and environmental causes. However, recent work has focused mostly on environmental sources of variation (Ketterson and Nolan 1994, Gowaty 1996a), and individual birds often are viewed as decision-making machines that respond adaptively to changes in their physical or social environments (Winkler and Wilkinson 1988). Indeed, birds modify parental effort in response to numerous proximate factors, including genetic parentage (Lifjeld et al. 1998), brood size (Ruusila and P6ysa 1998), and offspring age and condition (Whittingham and Robertson 1993). In no case have environmental factors accounted completely for differences among individuals in the intensity of parental care, however, and some role for genetic or cultural determination seems likely. For quantitative traits, genetic and environmental effects can be distinguished by examining the phenotypic resemblance of relatives. In cases of high narrow-sense heritability (h2), additive genetic effects contribute substantially to overall phenotypic variation, and relatives strongly covary (Falconer and Mackay 1996). Among vertebrates, estimates of heritability are lacking for measures of parental effort and for most quantitative behaviors in the field (Hailman 1986, Boag and van Noordwijk 1987, Mousseau and Roff 1987; but see Waser and Jones 1989). In general, heritabilities for behavioral traits are low (Lemon 1993, Berthold and Pulido 1994), suggesting that quantitative differences among individuals are largely driven by the environment. Here, we examine the degree to which male and female feeding rates are heritable in an insular population of Savannah Sparrows (Passerculus sandwichensis). We show that quantitative differences in feeding rates among males can be attributed to the be-

Evolution of resource allocation between growth and reproduction in animals with indeterminate growth

Abstract We review the recent theoretical developments explaining the evolution of age-schedules of reproduction in animals with indeterminate growth. Indeterminate growth, i.e. growth that continues past maturation and may continue until the end of life, is characteristic for a large number of invertebrate taxa (e.g. clams, cladocerans and crayfish) and ‘lower’ vertebrate taxa (e.g. fish, amphibians, lizards and snakes). Many plants also exhibit indeterminate growth, and we liberally include studies focused on plants when they can be interpreted in terms of animal life histories. We focus on different measures used to determine the fittest life histories, on indeterminate growth as a problem of resource allocation and on the effects of environment to the evolution of the resource allocation schemes.

Primate life histories

An animal's life history can be summarized by key variables that account for its life course from conception to death. Biological parameters that are of interest relate to reproductive effort and developmental rates (e.g., gestation length, neonatal weight, prenatal and postnatal growth rates, weaning age, and weaning weight) and the rate of reproduction (e.g., age at first and last reproduction, interbirth interval, the number of offspring per litter, birth rate, and the intrinsic rate of natural increase [rmax]). The rather obvious fact that such variables differ from species to species and from individual to individual has been the subject of much interest since the late 1960s, following the observation that species seem to be arranged in a spectrum that ranges from small animals that breed rapidly and develop early, have many young per litter, and have short lives, to large animals that breed slowly and develop late, have few young per litter, and have long lives. © 1998 Wiley-Liss, Inc.

Primate life histories

An animal's life history can be summarized by key variables that account for its life course from conception to death. Biological parameters that are of interest relate to reproductive effort and developmental rates (e.g., gestation length, neonatal weight, prenatal and postnatal growth rates, weaning age, and weaning weight) and the rate of reproduction (e.g., age at first and last reproduction, interbirth interval, the number of offspring per litter, birth rate, and the intrinsic rate of natural increase [rmax]). The rather obvious fact that such variables differ from species to species and from individual to individual has been the subject of much interest since the late 1960s, following the observation that species seem to be arranged in a spectrum that ranges from small animals that breed rapidly and develop early, have many young per litter, and have short lives, to large animals that breed slowly and develop late, have few young per litter, and have long lives. © 1998 Wiley-Liss, Inc.

Sexual Reproduction in the Colonial Kamptozoan Barentsia hildegardae

Four aspects of sexual reproduction were examined in a northeastern Pacific population of the kamptozoan (entoproct) Barentsia hildegardae. The investigation of this colonial species revealed that (1) the population was sexually mature year-round, with a peak of sexual maturity during summer; (2) the sex ratio of the calyces in this population did not differ significantly from 1:1 male:female; (3) male colonies grown on glass slides had higher proportions of sexually mature calyces than did females and the zone of maturity extended farther toward stolon tips; (4) recruitment was much higher near female than male colonies, perhaps because brooded larvae settled near their mothers almost immediately after release. Additional key words: Entoprocta, sexual maturation, reproductive period, sex ratio, larval period Understanding the life history of a colonial animal can be complicated, because processes such as growth, reproduction, and death must be examined at multiple levels (zooid, colony, and whole genet). Moreover, determining colony (and genet) boundaries in the field is often impossible. Consequently, we know far less about the life histories of colonial animals than about their unitary counterparts. Learning even basic information about colonial life histories, however, is essential for evolutionary and ecological studies of colonial

The origins of human ageing.

The origins of human ageing are to be found in the origins and evolution of senescence as a general feature in the life histories of higher animals. Ageing is an intriguing problem in evolutionary biology because a trait that limits the duration of life, including the fertile period, has a negative impact on Darwinian fitness. Current theory suggests that senescence occurs because the force of natural selection declines with age and because longevity is only acquired at some metabolic cost. In effect, organisms may trade late survival for enhanced reproductive investments in earlier life. The comparative study of ageing supports the general evolutionary theory and reveals that human senescence, while broadly similar to senescence in other mammalian species, has distinct features, such as menopause, that may derive from the interplay of biological and social evolution.

Adaptive Plasticity and Plasticity as an Adaptation: A Selective Review of Plasticity in Animal Morphology and Life History

During the last decade there has been a rapidly growing interest in the study of phenotypic plasticity in animals. Confused terminology in this field of research may be one reason why the focus of many studies is not as clear as it could be. The field of plasticity highlights the general problem of demonstrating adaptation. We discuss the terminology and methodology of plasticity studies, with particular reference to the question of which patterns should be considered evidence for plasticity as an adaptation to the environment, and how to find such evidence. We suggest a terminology where plasticity can be adaptive (i.e. beneficial, and maintained by selection) with respect to a function without strictly being an adaptation for it (evolutionary origin linked to this function), and vice versa. Modifications of the original reaction norm, seen today as differences in plasticity between populations and species, can be adaptations for a function even when the plasticity itself is not (it may follow from constraints or from selection for another function). We selectively review cases reported as evidence of adaptive plasticity in animal morphology and life history, choosing examples from a wide range of taxa to illustrate our criteria for what should be called adaptive and adaptation when applied to plasticity.

Adaptive plasticity in hatching age: a response to predation risk trade-offs.

The life histories of many animals are characterized by niche shifts, the timing of which can strongly affect fitness. In the tree frog Agalychnis callidryas, which has arboreal eggs, there is a trade-off between predation risks before and after hatching. When eggs are attacked by snakes, tadpoles escape by hatching rapidly and falling into the water below. Eggs not attacked by snakes hatch later, when newly emerged tadpoles are less vulnerable to aquatic predators. Plasticity in hatching allows embryos to use immediate, local information on risk of mortality to make instantaneous behavioral decisions about hatching and the accompanying shift from arboreal to aquatic habitats.

Hormones and the Physiological Architecture of Life History Evolution

Hormones play key roles in the regulation of animal and plant life histories, particularly in the timing of transitions between prematurational stages and in the scheduling of reproduction. Furthermore, hormonal mechanisms are subject to information about the external and internal environment of the individual. Within an evolutionary radiation, the same hormone subsets often regulate the schedules of development as well as adult reproduction and related activities and, moreover, are involved in mechanisms of senescence. We propose that the pleiotropic and epistatic effects from hormonal and neural mechanisms are an important substratum for life history evolution. This analysis of hormonal mechanisms in senescence implicates a role for antagonistic pleiotropy in selection for particular subsets of hormonal mechanisms that can be traced throughout prematurational and postmaturational stages. In the example of the vertebrate MHC (major histocompatibility complex), polymorphic loci have been assembled with pleiotropic actions on several regulatory axes affecting reproduction and other fitness components. We argue that the MHC and other complex loci may be considered as life history gene complexes, with pleiotropic influences throughout the lifespan. While analyses of this kind might suggest that life histories could be evolutionarily rigid, in our interpretation the population genetics that is involved provides a theoretical basis for great flexibility in hormonal regulation during life history evolution. It is possible that life history evolution among taxonomic groups may sometimes be chaotic, which would frustrate strong inferences by the comparative method in the study of life histories between taxonomic groups.

Habitat and size of the Florida crown conch (Melongena corona Gmelin): Why big snails hang out at bars

Along the north Florida coast of the Gulf of Mexico, crown conchs, Melongena corona Gmelin, exhibit larger mean size and attain larger individual sizes on oyster bars than in adjacent salt marshes. Analysis of growth and movement of tagged conchs over 15 months showed net movement of larger individuals from the salt marsh to the oyster bar and more rapid growth on the oyster bar where conchs primarily ate oysters. Laboratory manipulation of diets of conchs from each habitat showed higher growth rates in those fed oysters (Crassostrea virginica Gmelin) as compared to those fed mussels (Geukensia demissa Dill.), a common salt marsh prey. Oyster bar and salt marsh crown conchs fed the same diet grew at similar rates, but these results remain inconclusive because early life histories (especially natal habitats) of the experimental animals were unknown. Faster growth rates of oyster bar conchs in concert with net movement of larger salt marsh conchs to oyster bars accounts for the local size differential observed in this study and may explain similar size differences seen elsewhere in similar habitats.