The population dynamics and energy allocations of the Gila topminnow, a small livebearing fish, were studied in two contrasting environments, a spring run of constant characteristics and a fluctuating desert wash. Topminnows grew and matured in two basic patterns. First, many fish in both areas matured the year after their birth. Second, spring fish born early in the breeding season grew rapidly, bred within five months, and died by eight months of age. Although spring fish assimilated more energy, wash fish actually expended more calories for growth and reproduction, partly because of lower maintenance costs. Reproductive effort of long-lived spring fish varied with age between 3.1 and 6.5%; whereas efforts of short-lived spring and wash fish increased steadily with age to 5.2 and 9.8%, respectively. Although spring fish produced eggs of higher energy content, females in both areas varied their investment per offspring, apparently tracking seasonal changes in the availability of food for fry. When long-lived spring fish experienced food shortage, they allocated less energy to both growth and reproduction; in contrast, wash and short-lived spring fish under similar conditions reduced only their growth allocation. The reproductive mass in spring fish appeared to be limited by food availability, incompletely filled the abdominal space, and reflected no tradeoff between fecundity and investment per offspring. Reproduction by wash fish appeared to be limited by body space and was characterized by a tradeoff between fecundity and egg size.
Spring ephemerals in the Central Appalachians are a key component of deciduous forest communities and can be indicators of shifting phenology due to climate changes in this ecosystem. The objectives of this study were to (1) determine if there have been any changes in date of flowering for the Cutleaf Toothwort (Cardamine concatenata) and Yellow Trout Lily (Erythronium americanum) in West Virginia over the last 111 years; (2) determine which climatic factors affect the blooming date of these perennial, spring ephemeral wildflowers; and (3) evaluate the effect of elevation on changing blooming dates using herbarium specimens and photographs from 1904 to 2015. Both species are widespread throughout the woodlands of eastern North America. Both species have significantly advanced their spring flowering over the last century (x = 0.91 days/decade). Spring temperature was the strongest predictor of blooming date (2.91 and 3.44 days earlier/1°C increase in spring temperature, respectively). Flowers at \ 500 m elevation bloomed earlier and demonstrated a stronger shift in flowering date over time than flowers at [ 1000 m elevations. Lower elevations, higher spring and winter temperatures, and low amounts of precipitation were associated with earlier spring flowering. This research demonstrates the plasticity of phenological response to a variety of climatic variables, the usefulness of using herbarium specimens to reconstruct flowering dates over a topographically variable area, and the contrasting effects of climate change on high elevation regions of West Virginia.
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