scholarly journals Greater reproductive investment, but shorter lifespan, in agrosystem than in natural-habitat toads

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3791 ◽  
Author(s):  
Francisco Javier Zamora-Camacho ◽  
Mar Comas
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Prey Availability ◽  
Natural Habitat ◽  
Reproductive Investment ◽  
Emerging Diseases ◽  
Life Cycles ◽  
Habitat Alterations ◽  
Individual Fitness ◽  
Energy Trade

Global amphibian decline is due to several factors: habitat loss, anthropization, pollution, emerging diseases, and global warming. Amphibians, with complex life cycles, are particularly susceptible to habitat alterations, and their survival may be impaired in anthropized habitats. Increased mortality is a well-known consequence of anthropization. Life-history theory predicts higher reproductive investment when mortality is increased. In this work, we compared age, body size, and different indicators of reproductive investment, as well as prey availability, in natterjack toads (Epidalea calamita) from agrosystems and adjacent natural pine groves in Southwestern Spain. Mean age was lower in agrosystems than in pine groves, possibly as a consequence of increased mortality due to agrosystem environmental stressors. Remarkably, agrosystem toads were larger despite being younger, suggesting accelerated growth rate. Although we detected no differences in prey availability between habitats, artificial irrigation could shorten aestivation in agrosystems, thus increasing energy trade. Moreover, agrosystem toads exhibited increased indicators of reproductive investment. In the light of life-history theory, agrosystem toads might compensate for lesser reproductive events—due to shorter lives—with a higher reproductive investment in each attempt. Our results show that agrosystems may alter demography, which may have complex consequences on both individual fitness and population stability.

Testing Williams’ prediction: reproductive effort versus residual reproductive value (RRV)

2010 ◽  
Vol 88 (9) ◽  
pp. 900-904
Author(s):  
F. Stephen Dobson ◽  
Pierre Jouventin
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Reproductive Investment ◽  
Positive Association ◽  
Positive Influence ◽  
Life Cycles ◽  
Reproductive Value ◽  
Residual Reproductive Value ◽  
Trade Offs ◽  
Survival And Reproduction

Williams (1966; Am. Nat. 100(916): 687–690) furthered R.A. Fisher’s concept of reproductive value by breaking it into two components: (1) current reproduction and (2) residual reproductive value (RRV, the summed product of survival and reproduction over the rest of the lifespan). He predicted a negative correlation of measures of these two components among species, and this prediction led in part to the idea of trade-offs in life-history theory. We tested Williams’ prediction with 24 species of albatrosses and petrels (order Procellariiformes), species with a great range of body sizes and all laying only one egg at a time (like humans, highly iteroparous). Two measures of reproductive investment were not negatively correlated with RRV. Adjusting data for body mass and phylogeny resulted in significant positive associations. In addition, any measure of annual parental allocation to reproduction (once adjusted for body size) should give a positive association with RRV as shown by a simple simulation model that assumes a highly iteroparous life cycle. Under such life cycles, Williams’ prediction confounds the positive influence of reproduction on both current investment and RRV. Principles of life-history theory, however, do not require re-evaluation, as this particular prediction can in at least some cases be internally inconsistent.

Anuran life history plasticity: Variable practice in determining the end-point of larval development

2010 ◽  
Vol 31 (2) ◽  
pp. 157-167 ◽  
Author(s):  
Patrick Thomas Walsh
Keyword(s):  
Life History ◽  
Developmental Stages ◽  
Life Cycles ◽  
Developmental Phase ◽  
Larval Phase ◽  
End Point ◽  
Anuran Amphibians ◽  
Individual Fitness ◽  
Metamorphic Climax ◽  
Size At Metamorphosis

AbstractPlasticity in the timing of life history events and their impact on individual fitness, particularly the timing of and size at metamorphosis in animals with complex life cycles such as anuran amphibians, has long been of interest to ecologists. For different studies on life history plasticity to be comparable, there must be clearly defined and commonly agreed transition points, but it is unclear how consistently this is being performed in studies using anuran amphibians. In a review of 157 published studies, I found considerable variation in defining the end point of the larval phase. While a slight majority used the emergence of the forelimbs as the conclusion of the larval phase, some used a period within the developmental phase of metamorphic climax and others used the resorption of the tail. Studies included in this review, that assessed the same life history variable at two different developmental stages, reported some differences in results depending on which developmental stage was used. Recent evidence also shows that metamorphic climax is itself a period which can vary with environmental conditions, but, even in studies that included part or all of metamorphic climax in the larval phase, the treatment of individuals during metamorphic climax was not reported. Therefore, I argue that life history studies on anuran amphibians should distinguish the following phases: larval, metamorphic climax, juvenile, adult; that the end of the larval phase is best defined in ecological studies by forelimb emergence and that conditions under which individuals undergo metamorphic climax should be fully described.

Effect of body size, age and timing of breeding on clutch and egg size of female Eastern Gray Treefrogs, Hyla versicolor

2021 ◽  
pp. 1-11
Author(s):  
Gerlinde Höbel ◽  
Robb Kolodziej ◽  
Dustin Nelson ◽  
Christopher White
Keyword(s):  
Life History ◽  
Egg Size ◽  
Life History Theory ◽  
Reproductive Investment ◽  
Ecological Factors ◽  
Hyla Versicolor ◽  
Growth And Survival ◽  
Factors Affecting ◽  
Trade Offs ◽  
Gray Treefrogs

Abstract Information on how organisms allocate resources to reproduction is critical for understanding population dynamics. We collected clutch size (fecundity) and egg size data of female Eastern Gray Treefrogs, Hyla versicolor, and examined whether observed patterns of resource allocation are best explained by expectations arising from life history theory or by expected survival and growth benefits of breeding earlier. Female Hyla versicolor showed high between-individual variation in clutch and egg size. We did not observe maternal allocation trade-offs (size vs number; growth vs reproduction) predicted from life history theory, which we attribute to the large between-female variation in resource availability, and the low survival and post-maturity growth rate observed in the study population. Rather, clutches are larger at the beginning of the breeding season, and this variation in reproductive investment aligns with seasonal variation in ecological factors affecting offspring growth and survival.

scholarly journals Life-history traits and description of the new gonochoric amphimictic Mesobiotus joenssoni (Eutardigrada: Macrobiotidae) from the island of Elba, Italy

2019 ◽  
Author(s):  
Roberto Guidetti ◽  
Elisa Gneuß ◽  
Michele Cesari ◽  
Tiziana Altiero ◽  
Ralph O Schill
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Life History Traits ◽  
Life Cycles ◽  
Life History Strategies ◽  
Egg Hatching ◽  
Body Segments ◽  
Hatching Time ◽  
Laboratory Cultures ◽  
The Mean

Abstract Comparative analyses of life-history theory studies are based on the characteristics of the life cycles of different species. For tardigrades, life-history traits are available only from laboratory cultures, most of which have involved parthenogenetic species. The discovery of a new gonochoristic bisexual Mesobiotus species in a moss collected on the island of Elba (Italy) provides us with the opportunity to describe Mesobiotus joenssoni sp. nov. and to collect data on the life-history traits of cultured specimens to increase our knowledge of the life-history strategies present in tardigrades. This new species is differentiated from all other species of the genus by the presence of granules (~1 µm in diameter) on the dorsal cuticle of the last two body segments, two large bulges (gibbosities) on the hindlegs and long, conical egg processes. The species exhibits sexual dimorphism in body length, with females being longer than males of the same age. The mean lifespan of specimens was 86 days, with a maximum of 150 days. The mean age at first oviposition was 19.8 days and the mean egg hatching time 15.4 days. The life-cycle traits correspond to those collected for the only other two macrobiotid species with gonochoric amphimictic reproduction examined so far.

scholarly journals Indirect cues of nest predation risk and avian reproductive decisions

2009 ◽  
Vol 5 (2) ◽  
pp. 176-178 ◽  
Author(s):  
Mikko Mönkkönen ◽  
Jukka T Forsman ◽  
Tiina Kananoja ◽  
Hannu Ylönen
Keyword(s):  
Life History ◽  
Predation Risk ◽  
Clutch Size ◽  
Nest Predation ◽  
Life History Theory ◽  
Habitat Features ◽  
Nest Sites ◽  
Individual Fitness ◽  
Other Information ◽  
Indirect Cues

Current life-history theory predicts that increased mortality at early stages of life leads to reduced initial investment (e.g. clutch size) but increased subsequent investment during the reproduction attempt. In a field experiment, migratory pied flycatchers Ficedula hypoleuca perceived differences in mammalian nest predation risk and altered their reproductive strategies in two respects. First, birds avoided nest sites manipulated to reflect the presence of a predator. Second, birds breeding in risky areas nested 4 days earlier and laid 10 per cent larger clutches than those in safe areas, a result that runs counter to the prevailing life-history paradigm. We suggest that the overwhelming importance of nest predation to individual fitness reduces the value of collecting other information on habitat features leading to expedited onset of nesting, and, consequently, to larger clutch size.

scholarly journals Diet and divergence of introduced smallmouth bass (Micropterus dolomieu) populations

2005 ◽  
Vol 62 (8) ◽  
pp. 1720-1732 ◽  
Author(s):  
Erin S Dunlop ◽  
Judi A Orendorff ◽  
Brian J Shuter ◽  
F Helen Rodd ◽  
Mark S Ridgway
Keyword(s):  
Life History ◽  
Food Availability ◽  
Life History Theory ◽  
Reproductive Investment ◽  
Adult Mortality ◽  
Smallmouth Bass ◽  
Individual Growth ◽  
Common Source ◽  
Large Prey ◽  
Micropterus Dolomieu

We examine the degree and causes of divergence in growth and reproduction in two populations of smallmouth bass (Micropterus dolomieu) introduced a century ago. Despite a common source, the Provoking Lake population now has a higher population density and slower growing individuals than the Opeongo Lake population. Using this system, we test the predictions of life history theory that delayed maturation and reduced reproductive investment are expected in high density populations with slow individual growth rates. Observations on both populations run directly counter to the aforementioned expectations. Instead, Provoking males have smaller sizes and younger ages at nesting and higher gonad masses than Opeongo males; Provoking females have smaller sizes at maturity, larger egg sizes, and higher ovarian dry masses than Opeongo females. Temperature, food availability, diet ontogeny, young-of-the-year mortality, and adult mortality were examined as plausible contributors to the divergence. Results suggest that low food availability, likely caused or mediated by intraspecific competition for prey, and lack of large prey in the diet are contributing to the slow growth, increased reproductive investment, and higher mortality following reproduction in Provoking. This study provides insight into the processes that produce rapid divergence of life history in a species exhibiting parental care.

scholarly journals Cyclical environments drive variation in life history strategies: a general theory of cyclical phenology

2018 ◽  
Author(s):  
John S. Park
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Natural Populations ◽  
Life History Evolution ◽  
Life Cycles ◽  
Life History Strategies ◽  
Life History Variation ◽  
Trade Offs ◽  
Overwhelming Evidence ◽  
Phenological Shifts

ABSTRACTCycles, such as seasons or tides, characterize many systems in nature. Overwhelming evidence shows that climate change-driven alterations to environmental cycles—such as longer seasons— are associated with phenological shifts around the world, suggesting a deep link between environmental cycles and life cycles. However, general mechanisms of life history evolution in cyclical environments are still not well understood. Here I build a demographic framework and ask how life history strategies optimize fitness when the environment perturbs a structured population cyclically, and how strategies should change as cyclicality changes. I show that cycle periodicity alters optimality predictions of classic life history theory because repeated cycles have rippling selective consequences over time and generations. Notably, fitness landscapes that relate environmental cyclicality and life history optimality vary dramatically depending on which trade-offs govern a given species. The model tuned with known life history trade-offs in a marine intertidal copepod T. californicus successfully predicted the shape of life history variation across natural populations spanning a gradient of tidal periodicities. This framework shows how environmental cycles can drive life history variation—without complex assumptions of individual responses to cues such as temperature—thus expanding the range of life history diversity explained by theory and providing a basis for adaptive phenology.

Variation in the reproductive rate of bats

2004 ◽  
Vol 82 (5) ◽  
pp. 688-693 ◽  
Author(s):  
Robert M.R Barclay ◽  
Joel Ulmer ◽  
Cameron J.A MacKenzie ◽  
Megan S Thompson ◽  
Leif Olson ◽  
...  
Keyword(s):  
Life History ◽  
Life Histories ◽  
Life History Theory ◽  
Life History Traits ◽  
Prey Availability ◽  
Weather Conditions ◽  
Reproductive Rate ◽  
Tropical Species ◽  
Allocation Of Resources ◽  
Reproductive Rates

In many respects, bats have relatively slow life histories. However, the reproductive rate of bats (i.e., the proportion of females that reproduce in any breeding season) has not been critically examined. We compiled data on the reproductive rates of bats to test predictions based on life-history theory. Among 257 samples from 103 species, reproductive rate varied considerably and was typically under 100%. Temperate-zone species had significantly lower and more variable reproductive rates than did tropical species. Reproductive rate also varied among families, with species in the Vespertilionidae having particularly high rates. As predicted based on life-history theory, reproductive rate was negatively correlated with longevity, and among vespertilionids, species with larger litters had higher reproductive rates. Thus, the data suggest that bats have relatively slow reproductive rates and, as in other life-history traits, fall at the "slow" end of the fast–slow life-history continuum found among mammals. Female bats, especially those in temperate regions, appear to adjust their allocation of resources to reproduction, and at times forego reproduction, perhaps in relation to their body condition, prey availability, and weather conditions.

Life History Strategies

2018 ◽  
Author(s):  
Iris Wang ◽  
Nicholas Michael Michalak ◽  
Joshua Ackerman
Keyword(s):  
Resource Allocation ◽  
Life History ◽  
Life History Theory ◽  
Species Differences ◽  
Reproductive Investment ◽  
Life History Strategies ◽  
Investment In Reproduction

Life history theory posits organisms face tradeoffs in how they allocate resources to reproduction, parenting, and growth. These patterns of resource allocation can be classified more broadly into life history strategies, which vary on a continuum from fast to slow. These distinctions can be applied to describe within species and between species differences. Slow strategies are marked by increased investment in growth, a delay in reproductive investment, and increased investment in parenting. In contrast, fast strategies are marked by early investment in reproduction at a cost of growth and a reduced investment in parenting in favor of further reproduction.

scholarly journals Cyclical environments drive variation in life-history strategies: a general theory of cyclical phenology

2019 ◽  
Vol 286 (1898) ◽  
pp. 20190214 ◽  
Author(s):  
John S. Park
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Natural Populations ◽  
Life History Evolution ◽  
Life Cycles ◽  
Life History Strategies ◽  
Life History Variation ◽  
Trade Offs ◽  
Overwhelming Evidence ◽  
Phenological Shifts

Cycles, such as seasons or tides, characterize many systems in nature. Overwhelming evidence shows that climate change-driven alterations to environmental cycles—such as longer seasons—are associated with phenological shifts around the world, suggesting a deep link between environmental cycles and life cycles. However, general mechanisms of life-history evolution in cyclical environments are still not well understood. Here, I build a demographic framework and ask how life-history strategies optimize fitness when the environment perturbs a structured population cyclically and how strategies should change as cyclicality changes. I show that cycle periodicity alters optimality predictions of classic life-history theory because repeated cycles have rippling selective consequences over time and generations. Notably, fitness landscapes that relate environmental cyclicality and life-history optimality vary dramatically depending on which trade-offs govern a given species. The model tuned with known life-history trade-offs in a marine intertidal copepod Tigriopus californicus successfully predicted the shape of life-history variation across natural populations spanning a gradient of tidal periodicities. This framework shows how environmental cycles can drive life-history variation—without complex assumptions of individual responses to cues such as temperature—thus expanding the range of life-history diversity explained by theory and providing a basis for adaptive phenology.

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