The Adaptive Significance of Variations in Life History among Local Populations of Atlantic Salmon in North America

Ecology ◽  
1975 ◽  
Vol 56 (3) ◽  
pp. 577-590 ◽  
Author(s):  
William M. Schaffer ◽  
Paul F. Elson
Keyword(s):  
Life History ◽  
North America ◽  
Atlantic Salmon ◽  
Adaptive Significance ◽  
Local Populations

The adaptive significance of paedogenesis in North American species of Ambystoma (Amphibia: Caudata): an hypothesis

1974 ◽  
Vol 52 (3) ◽  
pp. 393-400 ◽  
Author(s):  
W. Gary Sprules
Keyword(s):  
Life History ◽  
North America ◽  
North American ◽  
Genetic Basis ◽  
Temperature Fluctuations ◽  
Adaptive Significance ◽  
Supporting Evidence ◽  
Low Humidity ◽  
Ambystomatid Salamanders ◽  
Harsh Conditions

Paedogenesis in varying degrees is exhibited by many species of North American salamanders, particularly of the genus Ambystoma. On the basis of a consideration of the ecology of these species, it is proposed that paedogenesis is evolutionarily adaptive and the following hypothesis is presented. In most habitats where ambystomatid salamanders occur, they exhibit the typical amphibian life history, consisting of aquatic larvae and terrestrial adults. However, where unusually harsh conditions, such as severe temperature fluctuations, lack of suitable cover or food, and low humidity, exist on land then the adjacent aquatic habitat is more suitable for salamanders provided it is permanent and provided fish are rare or absent. Under these circumstances paedogenesis will evolve because salamanders which spend their whole lives as larvae in the water have an adaptive advantage over those which metamorphose and become primarily terrestrial. Supporting evidence for the hypothesis is based primarily on patterns of similarity in the ecology of paedogenetic species of Ambystoma. It is suggested that paedogenesis is most commonly reported from the western mountains because this area contains more permanent fish-free ponds than any other area of North America. Exceptions to the hypothesis are discussed and some speculation on the genetic basis of paedogenesis is offered.

Effect of time of day, time of year, and life history strategy on time budgeting in juvenile Atlantic salmon, Salmo salar

1999 ◽  
Vol 56 (12) ◽  
pp. 2397-2403 ◽  
Author(s):  
Sveinn K Valdimarsson ◽  
Neil B Metcalfe
Keyword(s):  
Life History ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Life History Strategy ◽  
Time Of Day ◽  
Life History Strategies ◽  
Foraging Efficiency ◽  
Atlantic Salmon Salmo Salar ◽  
Juvenile Atlantic Salmon ◽  
Time Of Year

Traditionally, behavioural studies on juvenile Atlantic salmon, Salmo salar, have been conducted during the day in summer. It is known that Atlantic salmon become nocturnal in winter, but very little is known about their behaviour at that time. Therefore, observations in a seminatural stream were carried out during the day and night, from February to June, comparing diel and seasonal differences in behaviour between fish adopting alternative life history strategies. The results showed a general trend for more activity in spring than in winter, and the fish were found to be foraging at surprisingly low light levels. There were differences in relative feeding rate between the life history strategies; the early migrant fish foraged mostly during the day whereas the delayed migrant fish did more foraging at night. There is some evidence that the early migrant fish made fewer feeding attempts over the winter, which is surprising, since they grow faster over that period. This suggests differences in foraging efficiency, which could contribute to the separation into these two life history strategies.

Life History and Behavior of the Bramble Leafhopper, Ribautiana tenerrima (H.-S.) (Homoptera: Cicadellidae)

1960 ◽  
Vol 92 (1) ◽  
pp. 10-20 ◽  
Author(s):  
J. Raine
Keyword(s):  
Life History ◽  
North America ◽  
Vancouver Island ◽  
Dry Season ◽  
Lower Fraser Valley ◽  
And Behavior ◽  
Fraser Valley

Since 1947, when the bramble leafhopper, Ribautiana tenerrima (H.-S.) (rubi Hardy, misella 13011.), was first reported in North America near Victoria, B.C., it has become a serious pest in cane fruit plantings on southern Vancouver Island and the lower Fraser Valley. Hoth nymphs and adults suck the sap from the leaves, producing a white stippling on the upper surfaces (Fig. 1). In a dry season a severe infestation causes many leaves to become curled and appear burned. The canes lack vigor and the size of the fruit is reduced. This is a report on a study of the life history and behavior of the species conducted at Victoria from 1953 to 1957.

SYSTEMATICS OF THE TRICHADENOTECNUM ALEXANDERAE SPECIES COMPLEX (PSOCOPTERA: PSOCIDAE) BASED ON AN INVESTIGATION OF MODES OF REPRODUCTION AND MORPHOLOGY

1983 ◽  
Vol 115 (10) ◽  
pp. 1329-1354 ◽  
Author(s):  
B. W. Betz
Keyword(s):  
Life History ◽  
North America ◽  
Sibling Species ◽  
Species Complex ◽  
Morphological Analysis ◽  
Geographic Range ◽  
Eastern North America ◽  
Facultative Parthenogenesis

AbstractTrichadenotecnum alexanderae Sommerman is shown to represent one biparental (= euphrasic) species capable of facultative parthenogenesis (thelytoky) and three uniparental (= obligatorily parthenogenetic) sibling species, as determined by tests for mating, life history observations, and morphological analysis of specimens over the geographic range of the species complex. The name T. alexanderae is restricted to the biparental species because the holotype is a male. The three uniparental species are here named and described as T. castum n. sp., T. merum n. sp., and T. innuptum n. sp. The female of T. alexanderae is redescribed to allow its separation from the three uniparental species. A key to females of the species complex is supplied. All three uniparental species were derived from the biparental ancestor of T. alexanderae. Most collections of populations represented only by females consist of one or more uniparental species. Facultative parthenogenesis is shown to maintain a population of T. alexanderae through one generation only. The biparental species is found not to be restricted geographically to a relictual or peripheral range within the species complex, but to occupy a rather wide, north-temperate distribution across eastern North America.

scholarly journals An abdominal stridulation organ in Cyphoderris (Prophalangopsidae) and concerning the systematic classification of the Ensifera (Saltatoria)

2021 ◽  
Author(s):  
Kjell Ander
Keyword(s):  
North America ◽  
Adaptive Significance ◽  
Western North America ◽  
Systematic Classification ◽  
Mountainous Regions ◽  
Stridulatory Apparatus

Ensiferan insects (crickets, katydids, grigs and allies) are well known for rubbing parts of their cuticle together to produce sound: a process called stridulation. In this article Swedish entomologist Kjell Ander describes a novel (at the time) stridulatory apparatus in the great grig, Cyphoderris monstrosa (Prophalangopsidae), a relict ensiferan found in the mountainous regions of western North America. Ander used preserved specimens to predict the sound-producing function of a pair of abdominal file-scraper apparatuses, although he was never able to directly test his proposed mechanism nor did he speculate as to the adaptive significance of the structures. The article concludes with a review of the systematic placement of various higher level taxa within the order Orthoptera, of which Ensifera is one suborder.

Gene flow from domesticated escapes alters the life history of wild Atlantic salmon

2017 ◽  
Vol 1 (5) ◽  
Author(s):  
Geir H. Bolstad ◽  
Kjetil Hindar ◽  
Grethe Robertsen ◽  
Bror Jonsson ◽  
Harald Sægrov ◽  
...  
Keyword(s):  
Life History ◽  
Gene Flow ◽  
Atlantic Salmon ◽  
History Of
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