scholarly journals Species loss in developed landscapes: an experimental evaluation

2014 ◽  
Author(s):  
Alex Shepack ◽  
Kealoha Freidenburg ◽  
David Skelly
Keyword(s):  
Growth Rate ◽  
Experimental Evaluation ◽  
Rana Sylvatica ◽  
Development Rate ◽  
Wood Frog ◽  
Species Loss ◽  
Landscape Development ◽  
Wood Frogs ◽  
Lithobates Sylvaticus ◽  
Human Use

Conversion of landscapes for human uses is widely associated with loss of biodiversity. Here we focus on limits to distribution defined by intensity of landscape development. Using a translocation experiment, we ask does degradation of wetland habitat contribute to species loss? Wood frog larvae (Rana sylvatica = Lithobates sylvaticus), were reared within enclosures in 7 ponds harboring populations of wood frogs and in 5 ponds where they are absent. Survival, growth rate, and development rate were equivalent between ‘present’ and ‘absent’ ponds. While it is clear that landscapes surrounding ‘absent’ ponds had been heavily influenced by human use, we find no evidence that such wetlands provide inferior habitat for wood frog recruitment. Their absence in human altered landscapes may stem from influences outside of pond basins. The results provide a caution to the typically unexamined presumption that relictual habitats in developed landscapes are degraded in their utility for wildlife.

scholarly journals Species loss in developed landscapes: an experimental evaluation

2014 ◽  
Author(s):  
Alex Shepack ◽  
Kealoha Freidenburg ◽  
David Skelly
Keyword(s):  
Growth Rate ◽  
Experimental Evaluation ◽  
Rana Sylvatica ◽  
Development Rate ◽  
Wood Frog ◽  
Species Loss ◽  
Landscape Development ◽  
Wood Frogs ◽  
Lithobates Sylvaticus ◽  
Human Use

Conversion of landscapes for human uses is widely associated with loss of biodiversity. Here we focus on limits to distribution defined by intensity of landscape development. Using a translocation experiment, we ask does degradation of wetland habitat contribute to species loss? Wood frog larvae (Rana sylvatica = Lithobates sylvaticus), were reared within enclosures in 7 ponds harboring populations of wood frogs and in 5 ponds where they are absent. Survival, growth rate, and development rate were equivalent between ‘present’ and ‘absent’ ponds. While it is clear that landscapes surrounding ‘absent’ ponds had been heavily influenced by human use, we find no evidence that such wetlands provide inferior habitat for wood frog recruitment. Their absence in human altered landscapes may stem from influences outside of pond basins. The results provide a caution to the typically unexamined presumption that relictual habitats in developed landscapes are degraded in their utility for wildlife.

Sexual differences in color and color change in wood frogs

1991 ◽  
Vol 69 (7) ◽  
pp. 1963-1968 ◽  
Author(s):  
Richard B. King ◽  
Bethia King
Keyword(s):  
Color Change ◽  
Red Light ◽  
Green Light ◽  
Rana Sylvatica ◽  
Sexual Differences ◽  
Wood Frog ◽  
Color Classification ◽  
Wood Frogs ◽  
Evolutionary Response ◽  
Males And Females

An observer-free method of color classification was used to determine whether wood frogs, Rana sylvatica, exhibit sexual differences in color and color change. Males and females captured from breeding aggregations differed significantly in color: females reflected a greater amount of long-wavelength (yellow–red) light and less short-wavelength (blue–green) light than males. The color difference was not just a result of differences in the state of physiological color change at the time of capture but persisted for a month after capture. Males and females also differed in their color-change responses to black and white backgrounds: both sexes changed in brightness, but only males changed in the relative amount of light reflected at different wavelengths. Wood frog color may function in predator avoidance through crypsis. There was a good match between frogs and some of the leaves from the leaf litter surrounding the breeding ponds. Hypotheses for the development of sexual differences in wood frog color include sexual differences in availability of pigment and pigment precursors, morphological color change, and evolutionary response to different selection pressures.

Lack of an association between heterozygosity and growth rate in the wood frog, Rana sylvatica

1995 ◽  
Vol 73 (3) ◽  
pp. 569-575 ◽  
Author(s):  
Michael F. Wright ◽  
Sheldon I. Guttman
Keyword(s):  
Growth Rate ◽  
Multiple Regression ◽  
Rana Sylvatica ◽  
Developmental Period ◽  
Wood Frog ◽  
Single Locus ◽  
Regression Analyses ◽  
Enzyme Loci ◽  
Effect On Growth

The effect of both multilocus and single-locus heterozygosity on growth rate was examined in a cohort of larvae of the wood frog, Rana sylvatica, collected from a pond during the later stages of premetamorphic development. Seven electrophoretically detected enzyme loci were used to determine individual heterozygosity, whereas the growth rate was measured as wet mass. In all cases, no significant correlation was found between multilocus heterozygosity and mass among larvae collected at intervals during the developmental period. In addition, multiple regression analyses indicated that no single locus had a demonstrable effect on growth rate. The results of this study, therefore, provide no evidence for a link between enzyme heterozygosity and growth rate during the later stages of premetamorphic development in wood frog larvae.

Variation in acid tolerance of Connecticut wood frogs: genetic and maternal effects

1985 ◽  
Vol 63 (7) ◽  
pp. 1647-1651 ◽  
Author(s):  
Benjamin A. Pierce ◽  
Nalin Sikand
Keyword(s):  
Genetic Variation ◽  
Acidic Solution ◽  
Acid Tolerance ◽  
Rana Sylvatica ◽  
Larval Survival ◽  
Wood Frog ◽  
Maternal Factors ◽  
Wood Frogs ◽  
Significant Difference ◽  
Sib Families

Acid tolerance in wood frog (Rana sylvatica) embryos and larvae was examined in full- and half-sib families. Among the embryos, no significant difference in acid tolerance at pH 3.75 was observed among the progeny of males. At pH 4 only slight differences in embryo acid tolerance existed among the progeny of males mated to the same female. Thus, there is relatively little direct genetic variation in embryo acid tolerance. However, progeny from different females differed significantly in their acid tolerance at both pH 4 and pH 3.75, indicating that maternal factors are important in embryo acid tolerance. Whether these maternal factors are genetic is not known. Among larvae, maternal factors did not appear to influence acid tolerance, but significant genetic variation was present. Larval survival in an acidic solution was not correlated with embryo acid tolerance.

The effects of food and density on growth and metamorphosis in larval wood frogs (Rana sylvatica) from central Labrador

1990 ◽  
Vol 68 (6) ◽  
pp. 1221-1226 ◽  
Author(s):  
Dennis L. Murray
Keyword(s):  
Growth Rate ◽  
Larval Stage ◽  
Larval Density ◽  
Life History Strategy ◽  
Rana Sylvatica ◽  
Food Density ◽  
Immature Stages ◽  
Growth Inhibitors ◽  
Wood Frogs ◽  
Positive Effects

Two experiments were performed on Rana sylvatica tadpoles from central Labrador to test for effects of food and density on growth and metamorphosis. In an experiment examining for the presence of diffusible growth inhibitors, one group of tadpoles was given water treated by adding a high density of sibling tadpoles, and another group was given filtered lake water. No diffusible growth inhibitors existed in this population, as body weight measured weekly, weight at metamorphosis, and duration of larval stage did not differ between control and treated groups. In a food-density experiment, effects of food and larval density were examined by subjecting tadpoles at four different densities to four food levels, creating a 4 × 4 food–density matrix. Food and density both affected growth rate, weight at metamorphosis, and duration of larval stage. Socially governed negative density-dependent interactions are either nonexistent in northern populations, or were completely masked by slight positive effects of grouping. Results suggest that northern larvae differ in life-history strategy from southern populations, and the possibility of overwintering in immature stages of high-latitude populations is discussed.

Expression profiles of metamorphosis-related genes during natural transformations in tadpoles of wild Wood Frogs (Lithobates sylvaticus)

2012 ◽  
Vol 90 (9) ◽  
pp. 1059-1071 ◽  
Author(s):  
Laia Navarro-Martín ◽  
Chantal Lanctôt ◽  
Christopher Edge ◽  
Jeff Houlahan ◽  
Vance L. Trudeau
Keyword(s):  
Gene Expression ◽  
Expression Profiles ◽  
Rana Sylvatica ◽  
Fold Increase ◽  
Gonadal Development ◽  
Specific Expression ◽  
Wood Frogs ◽  
Lithobates Sylvaticus ◽  
Expression Levels ◽  
Gene Expression Levels

Numerous studies using laboratory-reared tadpoles have shown the importance of thyroid hormones (TH), thyroid receptors (TR), and deiodinase (Dio) enzymes during anuran metamorphosis. Our study focuses on the analysis of thyroid-related genes in tadpoles of wild Wood Frogs ( Lithobates sylvaticus (LeConte, 1825); also known as Rana sylvatica (Cope, 1889)) during metamorphosis. Results showed that, in concordance with laboratory-reared studies, thyroid receptor beta (trb) gene expression profiles presented the most marked changes. At climax and compared with premetamorphic stages, brains, tails, and gonad–mesonephros complex (GMC) tissues increased trb expression levels 5-, 21-, and 41-fold, respectively (p < 0.05). In addition, gene expression levels of brain deiodinase type II and III showed opposite trends, where 3-fold decrease and 10-fold increase were, respectively, found. This finding supports the idea that thyroid hormone, as it has been demonstrated in laboratory-reared tadpoles, is also involved in natural metamorphosis in wild tadpoles. Interestingly, and contrary to our predictions, we observed that whole brain corticotropin-releasing factor (crf) and crf receptor 1 (crfr1) gene expression levels significantly decrease through metamorphosis in wild L. sylvaticus tadpoles. Further analyses are required to determine if a role of TH in the timing of anuran gonadal development exists, as well as the importance of cell-specific and tissue-specific expression of crf and crfr1 to metamorphosis.

The ability of wood frog eggs to withstand prolonged terrestrial stranding: an empirical study

1988 ◽  
Vol 66 (8) ◽  
pp. 1733-1735 ◽  
Author(s):  
Don C. Forester ◽  
David V. Lykens
Keyword(s):  
Thermal Stress ◽  
Rana Sylvatica ◽  
Thermal Exposure ◽  
Early Spring ◽  
Egg Laying ◽  
Wood Frog ◽  
Seasonal Precipitation ◽  
Wood Frogs ◽  
Egg Masses ◽  
Ephemeral Ponds

In Maryland, the wood frog, Rana sylvatica, oviposits in ephemeral ponds and pools during early spring. Seasonal precipitation is often unpredictable and egg masses may become exposed as ponds recede. The ability of wood frog eggs to withstand prolonged terrestrial exposure was tested in the laboratory. Egg mortality rate was exponential. Compared with a submerged control, 49% of the eggs died within 2 days, but 11% of the eggs were alive after 10 days and a few survived as long as 14 days. Wood frogs are thought to have evolved communal egg laying as a mechanism to minimize thermal stress during development. We suggest that this behavior also enabled egg masses to withstand terrestrial stranding. Today, advantages accrued through reduced thermal exposure and resistance to desiccation likely act in concert to stabilize communal egg-laying behavior.

Cold hardiness in two helminth parasites of the freeze-tolerant wood frog, Rana sylvatica

2000 ◽  
Vol 78 (6) ◽  
pp. 1085-1091 ◽  
Author(s):  
Douglas C Woodhams ◽  
Jon P Costanzo ◽  
Jonathan D Kelty ◽  
Richard E Lee, Jr.
Keyword(s):  
Cold Hardiness ◽  
Rana Sylvatica ◽  
Wood Frog ◽  
Digenetic Trematode ◽  
Helminth Parasites ◽  
Wood Frogs ◽  
Freeze Avoidance ◽  
Body Tissues ◽  
Freeze Tolerant

Wood frogs, Rana sylvatica, tolerate the freezing of their body tissues as an overwintering adaptation. Various parasites infect wood frogs of northern populations, but nothing is known about their strategies for surviving within a frozen host. We examined winter-conditioned wood frogs that were experimentally exposed to 0°C (nonfrozen) or –4°C (frozen) to determine whether endoparasites survive the freezing of their host. We found no differences in the prevalence or intensity of adult lungworms Rhabdias ranae (Nematoda) or of larvae of an unidentified species of digenetic trematode between these groups. Live individuals of both species were observed in hosts that recovered from experimental freezing at –4°C. Within the host, R. ranae also tolerated exposure to –5°C, a temperature near the lower limit of survival of the wood frog. Cryostage experiments showed that, like its host, R. ranae was highly susceptible to inoculative freezing and tolerant of the freezing of its tissues. Rhabdias ranae frozen in vitro in the presence or absence of 250 mM glucose, the cryoprotectant used by wood frogs, recovered from a 10-h exposure to –4°C. The mechanism of cold tolerance used by larval trematodes was not investigated; however, we hypothesize that freeze avoidance by supercooling may be important in this species. Freeze-tolerant anurans, such as the wood frog, are useful subjects in the study of coevolution of thermal tolerance in parasites and their host.

Carryover effects of phenotypic plasticity: embryonic environment and larval response to predation risk in Wood Frogs (Lithobates sylvaticus) and Northern Leopard Frogs (Lithobates pipiens)

2015 ◽  
Vol 93 (11) ◽  
pp. 867-877 ◽  
Author(s):  
A.M. Bennett ◽  
D.L. Murray
Keyword(s):  
Predation Risk ◽  
Wood Frog ◽  
Leopard Frog ◽  
Carryover Effects ◽  
Wood Frogs ◽  
Lithobates Sylvaticus ◽  
Northern Leopard Frog ◽  
Leopard Frogs ◽  
Frog Tadpoles ◽  
Northern Leopard Frogs

Limitations of phenotypic plasticity affect the success of individuals and populations in changing environments. We assessed the plasticity-history limitation on predator-induced defenses in anurans (Wood Frogs, Lithobates sylvaticus (LeConte, 1825), and Northern Leopard Frogs, Lithobates pipiens (Schreber, 1782)), predicting that plastic responses to predation risk by dragonfly larvae (family Aeshnidae) in the embryonic environment would limit the defensive response to predators in the larval environment. Predator-conditioned Wood Frog embryos increased relative tail depth in response to those same cues as larvae, whereas predator-naive tadpoles did not. However, no carryover effect was noted in the behavioural response of Wood Frog tadpoles to predation risk. Predator-naive Northern Leopard Frog tadpoles increased relative tail depth in response to predation risk in the larval environment. Predator-conditioned Northern Leopard Frog embryos hatched with, and maintained, a marginal increase in tail depth as larvae in the absence of predation risk. Predator-conditioned Northern Leopard Frog embryos exposed to predation risk as larvae showed no morphological response. While we find no strong support for the plasticity-history limitation per se, carryover effects across embryonic and larval life-history stages were noted in both Wood Frog and Northern Leopard Frog, suggesting that predation risk early in ontogeny can influence the outcome of future interactions with predators.

Physiological and ecological aspects of low-temperature tolerance in embryos of the wood frog, Rana sylvatica

2000 ◽  
Vol 78 (6) ◽  
pp. 1032-1041 ◽  
Author(s):  
Malcolm Pratt Frisbie ◽  
Jon P Costanzo ◽  
Richard E Lee, Jr.
Keyword(s):  
Water Column ◽  
Rana Sylvatica ◽  
Wood Frog ◽  
Temporary Ponds ◽  
Late Winter ◽  
Daily Maximum ◽  
Similar Degree ◽  
Wood Frogs ◽  
Daily Minimum ◽  
Subzero Temperatures

Wood frogs (Rana sylvatica) breed in late winter in temporary ponds, where eggs are deposited in communal surface rafts. Subsequently, developing embryos may face subzero temperatures. In the laboratory, individual embryos supercooled moderately (to –4.2°C for embryos in their jelly capsules; to –5.0°C for embryos removed from the jelly capsule) when chilled in the absence of external ice nuclei, but did not resist inoculative freezing when chilled in contact with external ice. They survived acute episodes (1–18 h) of supercooling to temperatures between ca. –0.5 and –2.0°C. Stage-12 embryos (six of six) survived freezing for 1 h at –2.0°C, but only one of six survived a 3.5-h freezing episode at the same temperature. Stage-13 and -14 embryos survived freezing episodes of 4.5 h at –1.0°C (six of six survived) and 18 h at –0.5°C (six of six survived), respectively. In the field, temperatures were monitored every 5 min for 21 d in embryo masses of wood frogs and Jefferson salamanders (Ambystoma jeffersonianum) at a breeding pond in central Kentucky. Wood frog embryos experienced higher daily maximum and lower daily minimum temperatures than salamander embryos, which were deeper in the water column. Wood frog embryos spent more time at risk of cryoinjury (i.e., at temperatures [Formula: see text]1°C), but the two species accumulated similar degree-days over the 21-d observation period. Their position in the water column may permit wood frogs to garner a developmental advantage in milder years, when daily minimum temperatures are similar between the two species. Wood frog embryos appear to offset some of the risks associated with this more exposed position by tolerating somatic freezing at high subzero temperatures.

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