Density-dependent polyphenism and geographic variation in size among two populations of lubber grasshoppers (Romalea microptera)

2009 ◽  
Vol 34 (5) ◽  
pp. 644-651 ◽  
Author(s):  
JASON E. JANNOT ◽  
ALEXANDER E. KO ◽  
DUSTIN L. HERRMANN ◽  
LAURA SKINNER ◽  
EMILY BUTZEN ◽  
...  
Keyword(s):  
Geographic Variation ◽  
Density Dependent ◽  
Two Populations

scholarly journals Geographic variation in the morphology of the sand-dwelling lizard Nothobachia ablephara (Squamata: Gymnophthalmidae)

2019 ◽  
Vol 18 (2) ◽  
pp. 195-207
Author(s):  
Carolina Nisa Ramiro ◽  
Renato Sousa Recoder ◽  
Miguel Trefaut Rodrigues
Keyword(s):  
Geographic Variation ◽  
Morphological Traits ◽  
Geographical Variation ◽  
Multivariate Analyses ◽  
Molecular Study ◽  
Northeastern Brazil ◽  
Sexually Dimorphic ◽  
Morphometric Variation ◽  
The One ◽  
Two Populations

Geographic variation in the morphology of the sand-dwelling lizard Nothobachia ablephara (Squamata: Gymnophthalmidae). Nothobachia ablephara is a small microteiid lizard with an elongated body and reduced limbs; it occurs in isolated dune felds in the state of Bahia (Xique-Xique and Alagoado) and small sandy patches in northeastern Brazil. A previous molecular study found a marked mtDNA divergence between populations of N. ablephara from Alagoado and Xique-Xique dunes, suggesting that the two populations diverged from one another between 3 and 4 million years ago. Given this isolation, it is interesting to explore whether morphological traits of the lizards refect the reported genetic divergence of the populations. Scale counts of the sexes and the populations differ signifcantly, but there is considerable overlap of values. Univariate and multivariate analyses revealed signifcant morphometric variation between sexes and populations; however, this is mostly explained by size differences. Females are larger than males in all characters that are sexually dimorphic, and individuals from Xique-Xique are larger than those from Alagoado in all characters that vary geographically. The sample from Alagoado has more sexually dimorphic characters than the one from Xique-Xique. Although N. ablephara displays some geographical variation, the two populations could not be unequivocally distinguished by scale counts and morphometric data.

Geographic variation in the advertisement call of Crinia signifera (Anura:Myobatrachidae) on Kangaroo Island and across southern south-eastern Australia

2008 ◽  
Vol 56 (4) ◽  
pp. 223 ◽  
Author(s):  
Murray J. Littlejohn
Keyword(s):  
Geographic Variation ◽  
Pulse Number ◽  
Advertisement Call ◽  
Regional Study ◽  
South Eastern ◽  
Island Sample ◽  
Eastern Australia ◽  
Continental Islands ◽  
Two Populations ◽  
South Eastern Australia

The male advertisement call of anuran amphibians has a major role in mate choice, and regional variation in this attribute can act as an indicator of speciation and a marker for genetic differentiation. As part of a regional study of geographic variation in the male advertisement call of Crinia signifera across south-eastern Australia and adjacent larger continental islands, samples of advertisement calls from two populations on Kangaroo Island and two populations on the adjacent Fleurieu Peninsula were compared. Four call attributes were considered: pulse number, call duration, pulse rate and dominant frequency. Pulse number is considered the most reliable for comparative purposes because it is not influenced by effective temperature or audio recording and analysis. The two island populations (central and eastern, ~24 km apart) differ significantly in pulse number, with contact but no overlap of interquartile ranges. The eastern sample differs markedly from those on the nearby Fleurieu Peninsula – which are both similar to the more distant central island sample. Geographic variation in pulse number in these four samples and 11 others from two recent publications is then interpreted in the light of land bridges and lower temperatures of the late Pleistocene and early Holocene.

Seasonal responses and their geographic variation in Chrysopa downesi: ecophysiological and evolutionary considerations

1981 ◽  
Vol 59 (3) ◽  
pp. 370-376 ◽  
Author(s):  
Maurice J. Tauber ◽  
Catherine A. Tauber
Keyword(s):  
New York ◽  
Geographic Variation ◽  
Thermal Thresholds ◽  
Preoviposition Period ◽  
Geographic Populations ◽  
Dark Green ◽  
Diapause Incidence ◽  
T Values ◽  
Two Populations ◽  
Seasonal Responses

A comparison of Chrysopa downesi strains from Montana and from New York indicates that they share several characteristics in their seasonal cycles: (1) a short-day – long-day requirement for diapause prevention, (2) dark green adult coloration all year round, (3) relatively high t values (lower thermal thresholds for development), and (4) sensitivity to photoperiod during the nondiapause preoviposition period.Responsiveness to prey differs between the two strains. Prey presence very slightly reduces diapause incidence and greatly shortens the nondiapause preoviposition period in the strain from Montana, whereas prey presence has little or no influence on the strain from the northeastern United States. The strains also differ in their ability to terminate diapause spontaneously; unlike the northeastern strain, a proportion of the northwestern strain ends diapause without an overt, external stimulus.The two populations of C. downesi thus share the two characteristics that are basic to the model of C. downesi's sympatric speciation from an ancestor like C. carnea. In contrast, the differences between the two populations in their responsiveness to prey presence parallels the geographic variation in C. carnea. We propose two alternate pathways (polyphyletic and monophyletic) for the evolution of the seasonal responses of the two geographic populations.

scholarly journals Reproductive investment in Atlantic cod populations off Newfoundland: Contrasting trends between males and females

FACETS ◽  
2017 ◽  
Vol 2 (2) ◽  
pp. 660-681 ◽  
Author(s):  
Loïc Baulier ◽  
M. Joanne Morgan ◽  
George R. Lilly ◽  
Ulf Dieckmann ◽  
Mikko Heino
Keyword(s):  
Life History Theory ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Temporal Trends ◽  
Reproductive Investment ◽  
Male Reproductive Success ◽  
Density Dependent ◽  
Theoretical Predictions ◽  
Two Populations

Life history theory predicts selection for higher reproductive investment in response to increased mortality among mature individuals. We tested this prediction over the period from 1978 to 2013 for three populations of Atlantic cod ( Gadus morhua) off Newfoundland. These populations were heavily fished for a long period. We considered changes in standardized gonad weight as a proxy for changes in gonadal investment. We accounted for the allometry between gonad and body weight, individual body condition, water temperature, and potential spatial and density-dependent effects. Males display significant temporal trends in gonadal investment in all populations; in agreement with theoretical predictions, these trends show increased gonadal investments during the earlier part of the time series when mortality was high, with the trends leveling off or reversing after the later imposition of fishing moratoria. In contrast, females display patterns that are less consistent and expected; significant trends are detected only when accounting for density-dependent effects, with females in two populations unexpectedly showing a long-term decline in gonadal investment. Our results support the hypothesis that fisheries-induced evolution has occurred in gonadal investment in males, but not in females, and suggest that gonadal investment is more important for male reproductive success than expected in this lekking species.

scholarly journals Geographic Variation in Liver Metal Concentrations of Greater Sage-Grouse

2013 ◽  
Vol 4 (2) ◽  
pp. 298-302 ◽  
Author(s):  
Erik J. Blomberg ◽  
Peregrine L. Wolff ◽  
James S. Sedinger
Keyword(s):  
Geographic Variation ◽  
Small Body ◽  
Selenium Deficiency ◽  
Local Variation ◽  
Sage Grouse ◽  
Tissue Concentrations ◽  
Metal Concentrations ◽  
Low Selenium ◽  
Two Populations ◽  
Regional Comparisons

Abstract Populations of greater sage-grouse (Centrocercus urophasianus) have declined throughout the species' range. We evaluated metal concentrations in livers sampled from greater sage-grouse collected from hunters in Eureka County, Nevada, during autumn of 2008 and 2010. We make local comparisons of metal concentrations between two populations of greater sage-grouse in Eureka County, as well as regional comparisons with previously reported values for greater sage-grouse collected in Wyoming and Montana. With one exception, tissue concentrations of lead, arsenic, and mercury were below method detection limits. Mean concentrations of iron, molybdenum, and zinc differed between the two Nevada populations, and magnesium, cadmium, molybdenum, and selenium differed between greater sage-grouse in eastern Nevada, and values reported for Wyoming and Montana. In contrast, we found no evidence for local variation in magnesium, copper, cadmium, or selenium, or for regional variation in iron, zinc, or copper. Of particular interest were low selenium concentrations in our study system relative to Wyoming and Montana. Some individuals in our study returned liver selenium values considered consistent with selenium deficiency in domestic poultry. This research adds to the small body of literature on background contaminant levels in greater sage-grouse, and provides evidence for geographic variation in metal concentrations at local and regional scales.

Influence of Density-Dependent Migration on Two Competitive Populations between Patches in Manufacturing Engineering

2011 ◽  
Vol 323 ◽  
pp. 247-251
Author(s):  
Zhi Qiang Ye ◽  
Xu Zhang
Keyword(s):  
Mathematical Model ◽  
Interspecific Competition ◽  
Computer Simulations ◽  
Positive Equilibrium ◽  
Density Dependent ◽  
Migration Rates ◽  
Manufacturing Engineering ◽  
Globally Stable ◽  
Two Populations

A mathematical model of two competitive populations with migrations between two patches in manufacturing engineering is proposed. It is assumed that migration rates of the two populations are not constants but density-dependent which are led mainly by the pressure from interspecific competition. Conditions for the persistence of the system are obtained which shows that appropriate migration rates facilitate the two competitive populations to cooperate well such that both the populations are persistent in every patch. The results are confirmed by computer simulations. It is also found that the positive equilibrium which is globally stable changes into bitable equilibrium as the parameters vary.

Geographic variation in density-dependent dynamics impacts the synchronizing effect of dispersal and regional stochasticity

2006 ◽  
Vol 48 (2) ◽  
pp. 131-138 ◽  
Author(s):  
Andrew M. Liebhold ◽  
Derek M. Johnson ◽  
Ottar N. Bjørnstad
Keyword(s):  
Geographic Variation ◽  
Density Dependent

scholarly journals Oviposition strategy as a means of local adaptation to plant defence in native and invasive populations of the viburnum leaf beetle

2011 ◽  
Vol 279 (1730) ◽  
pp. 952-958 ◽  
Author(s):  
Gaylord A. Desurmont ◽  
Franck Hérard ◽  
Anurag A. Agrawal
Keyword(s):  
Local Adaptation ◽  
Plant Defence ◽  
Leaf Beetle ◽  
Positive Density ◽  
Plant Defences ◽  
Viburnum Opulus ◽  
Density Dependent ◽  
Wound Responses ◽  
Pyrrhalta Viburni ◽  
Two Populations

Herbivores have been hypothesized to adapt locally to variation in plant defences and such adaptation could facilitate novel associations in the context of biological invasions. Here, we show that in the native range of the viburnum leaf beetle (VLB, Pyrrhalta viburni ), two populations of geographically isolated hosts— Viburnum opulus and Viburnum tinus —have divergent defences against VLB oviposition: negative versus positive density-dependent egg-crushing wound responses, respectively. Populations of beetles coexisting with each host show an adaptive behavioural response: aggregative versus non-aggregative oviposition on V. opulus and V. tinus , respectively. In parallel, we show that in North America, where VLB is invasive, defences of three novel hosts are negatively density-dependent, and beetles' oviposition behaviour is aggregative. Thus, local adaptation to plant defences has the potential to facilitate the invasion of herbivores onto novel hosts.

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