Elevational Range (elevational + range)

Distribution by Scientific Domains


Selected Abstracts


Ecological Traits Predicting Amphibian Population Declines in Central America

CONSERVATION BIOLOGY, Issue 4 2003
Karen R. Lips
Populations of some species are extirpated, others have declined but survive, some have not obviously declined, and some are increasing. If amphibian populations at multiple sites were affected by the same factors, then surviving species should share traits that promote persistence, whereas declining species should share traits that promote susceptibility. Identifying these traits can help diagnose potential causes and thus help to direct conservation actions. Using logistic regression, we quantified the vulnerability of amphibian populations in four areas in Central America. We analyzed a species-specific database of taxonomic identity, geographic and elevational range, elevational distribution, adult and larval habitat, activity period, and maximum adult body size. We found that ( 1 ) all four sites exhibited the same pattern of decline ( there were no interactions between site and other variables ); ( 2 ) declining populations shared aquatic habitats, restricted elevational ranges, and large body sizes; and ( 3 ) there was an interaction between body size and elevational range. The most significant variable in the model was lifetime aquatic index, a factor unrelated to demographic vulnerability and one that therefore might indicate the potential causative agent( s ). Our results provide a predictive model with which to assess potential causes of population declines in other areas, and we generated a list of 52 species predicted to decline at a currently unaffected site in central Panama. Resumen: Las poblaciones de anfibios están declinando en todos los continentes donde ocurren, pero no todas las especies han sido afectadas por igual. Algunas especies han sido extirpadas, otras han declinado pero sobreviven, algunas no han declinado notablemente y otras están aumentando. Si las poblaciones de anfibios en varios sitios fueran afectadas por los mismos factores, las especies sobrevivientes deberían compartir características que promuevan la persistencia mientras que las especies en declinación deberían compartir características que promuevan la susceptibilidad. La identificación de estas características puede ayudar a diagnosticar las causas potenciales y así ayudar a dirigir medidas de conservación. Utilizando regresión logística, cuantificamos la vulnerabilidad de las poblaciones de anfibios en cuatro áreas de Centro América. Analizamos una base de datos de identidad taxonómica de especies, rango geográfico y altitudinal, distribución altitudinal, hábitat de larvas y adultos, período de actividad y máxima talla corporal de adultos. Encontramos que ( 1 ) los cuatro sitios presentaron el mismo patrón de declinación ( no hubo interacciones entre el sitio y otras variables ), ( 2 ) las poblaciones en declinación compartieron hábitats acuáticos, rangos altitudinales restringidos y tamaño corporal grande y ( 3 ) hubo interacción entre el tamaño corporal y el rango altitudinal. La variable más significativa del modelo fue el índice de vida acuática, un factor no relacionado con la vulnerabilidad demográfica y que, por lo tanto, podría indicar el agente causal potencial. Nuestros resultados proporcionan un modelo predictivo para evaluar las causas potenciales de declinación poblacional en otras áreas, y generamos una lista de 52 especies de declinación prevista en un sitio actualmente no afectado del centro de Panamá. [source]


TESTING THE ROLE OF INTERSPECIFIC COMPETITION IN THE EVOLUTIONARY ORIGIN OF ELEVATIONAL ZONATION: AN EXAMPLE WITH BUARREMON BRUSH-FINCHES (AVES, EMBERIZIDAE) IN THE NEOTROPICAL MOUNTAINS

EVOLUTION, Issue 5 2007
Carlos Daniel Cadena
Interspecific competition might drive the evolution of ecological niches and result in pairs of formerly competing species segregating along ecological gradients following a process of character displacement. This mechanism has been proposed to account for replacement of related species along gradients of elevation in many areas of the world, but the fundamental issue of whether competition is responsible for the origin of elevational replacements has not been tested. To test hypotheses about the role of interspecific competition in the origin of complementary elevational ranges, I combined molecular phylogenetics, phylogeography, and population genetic analyses on Buarremon torquatus and B. brunneinucha (Aves, Emberizidae), whose patterns of elevational distribution suggest character displacement or ecological release. The hypothesis that elevational distributions in these species changed in opposite directions as a result of competition is untenable because: (1) a historical expansion of the range of B. brunneinucha into areas occupied by B. torquatus was not accompanied by a shift in the elevational range of the former species; (2) when B. brunneinucha colonized the range of B. torquatus, lineages of the latter distributions had already diverged; and (3) historical trends in effective population size do not suggest populations with elevational ranges abutting those of putative competitors have declined as would be expected if competition caused range contractions. However, owing to uncertainty in coalescent estimates of historical population sizes, the hypothesis that some populations of B. torquatus have declined cannot be confidently rejected, which suggests asymmetric character displacement might have occurred. I suggest that the main role of competition in elevational zonation may be to act as a sorting mechanism that allows the coexistence along mountain slopes only of ecologically similar species that differ in elevational distributions prior to attaining sympatry. The contrasting biogeographic histories of B. brunneinucha and B. torquatus illustrate how present-day ecological interactions can have recent origins, and highlights important challenges for testing the hypothesis of character displacement in the absence of data on population history and robust reconstructions of the evolution of traits and geographic ranges. [source]


THE EVOLUTION OF WING COLOR: MALE MATE CHOICE OPPOSES ADAPTIVE WING COLOR DIVERGENCE IN COLIAS BUTTERFLIES

EVOLUTION, Issue 5 2003
Jacintha Ellers
Abstract Correlated evolution of mate signals and mate preference may be constrained if selection pressures acting on mate preference differ from those acting on mate signals. In particular, opposing selection pressures may act on mate preference and signals when traits have sexual as well as nonsexual functions. In the butterfly Colias philodice eriphyle, divergent selection on wing color across an elevational gradient in response to the thermal environment has led to increasing wing melanization at higher elevations. Wing color is also a long-range signal used by males in mate searching. We conducted experiments to test whether sexual selection on wing melanization via male mate choice acts in the same direction as natural selection on mate signals due to the thermal environment. We performed controlled mate choice experiments in the field over an elevational range of 1500 meters using decoy butterflies with different melanization levels. Also, we obtained a more direct estimate of the relation between wing color and sexual selection by measuring mating success in wild-caught females. Both our experiments showed that wing melanization is an important determinant of female mating success in C. p. eriphyle. However, a lack of elevational variation in male mate preference prevents coevolution of mate signals and mate preference, as males at all elevations prefer less-melanized females. We suggest that this apparently maladaptive mate choice may be maintained by differences in detectability between the morphs or by preservation of species recognition. [source]


Combined effects of climate and biotic interactions on the elevational range of a phytophagous insect

JOURNAL OF ANIMAL ECOLOGY, Issue 1 2008
Richard M. Merrill
Summary 1The ranges of many species have expanded in cool regions but contracted at warm margins in response to recent climate warming, but the mechanisms behind such changes remain unclear. Particular debate concerns the roles of direct climatic limitation vs. the effects of interacting species in explaining the location of low latitude or low elevation range margins. 2The mountains of the Sierra de Guadarrama (central Spain) include both cool and warm range margins for the black-veined white butterfly, Aporia crataegi, which has disappeared from low elevations since the 1970s without colonizing the highest elevations. 3We found that the current upper elevation limit to A. crataegi's distribution coincided closely with that of its host plants, but that the species was absent from elevations below 900 m, even where host plants were present. The density of A. crataegi per host plant increased with elevation, but overall abundance of the species declined at high elevations where host plants were rare. 4The flight period of A. crataegi was later at higher elevations, meaning that butterflies in higher populations flew at hotter times of year; nevertheless, daytime temperatures for the month of peak flight decreased by 6·2 °C per 1 km increase in elevation. 5At higher elevations A. crataegi eggs were laid on the south side of host plants (expected to correspond to hotter microclimates), whereas at lower sites the (cooler) north side of plants was selected. Field transplant experiments showed that egg survival increased with elevation. 6Climatic limitation is the most likely explanation for the low elevation range margin of A. crataegi, whereas the absence of host plants from high elevations sets the upper limit. This contrasts with the frequent assumption that biotic interactions typically determine warm range margins, and thermal limitation cool margins. 7Studies that have modelled distribution changes in response to climate change may have underestimated declines for many specialist species, because range contractions will be exacerbated by mismatch between the future distribution of suitable climate space and the availability of resources such as host plants. [source]


Can differences in autonomous selfing ability explain differences in range size among sister-taxa pairs of Collinsia (Plantaginaceae)?

NEW PHYTOLOGIST, Issue 3 2009
An extension of Baker's Law
Summary ,,Species with greater selfing ability are predicted to be better adapted for colonizing new habitats (Baker's Law). Here, we tested an expansion of this hypothesis: that species proficient at autonomous selfing have larger range sizes than their less proficient sister taxa. We also tested competing hypotheses regarding seed production and niche breadth on range size. ,,Floral traits affecting the proficiency of autonomous selfing were measured and seed production was calculated for six sister-taxa pairs in the clade Collinsia. We tested for the hypothesized effects of these variables on elevational distribution and range size. ,,We found that species most proficient at selfing had significantly larger range sizes than their sister-taxa that were less proficient at selfing. Species proficient at autonomous selfing occupied a higher mean elevation than their sister taxa, but they did not differ in their total elevational range. Species with greater seed production did not have larger range sizes. ,,Our results extend Baker's Law, suggesting that species proficient at autonomous selfing are better adapted to establish new populations and thus can more readily expand their range. Autonomous selfing ability may play a vital role in explaining variance in range size among other species. [source]


Forest Regeneration in a Chronosequence of Tropical Abandoned Pastures: Implications for Restoration Ecology

RESTORATION ECOLOGY, Issue 4 2000
T. Mitchell Aide
Abstract During the mid-1900s, most of the island of Puerto Rico was deforested, but a shift in the economy from agriculture to small industry beginning in the 1950s resulted in the abandonment of agricultural lands and recovery of secondary forest. This unique history provides an excellent opportunity to study secondary forest succession and suggest strategies for tropical forest restoration. To determine the pattern of secondary succession, we describe the woody vegetation in 71 abandoned pastures and forest sites in four regions of Puerto Rico. The density, basal area, aboveground biomass, and species richness of the secondary forest sites were similar to those of the old growth forest sites (>80 yr) after approximately 40 years. The dominant species that colonized recently abandoned pastures occurred over a broad elevational range and are widespread in the neotropics. The species richness of Puerto Rican secondary forests recovered rapidly, but the species composition was quite different in comparison with old growth forest sites, suggesting that enrichment planting will be necessary to restore the original composition. Exotic species were some of the most abundant species in the secondary forest, but their long-term impact depended on life history characteristics of each species. These data demonstrate that one restoration strategy for tropical forest in abandoned pastures is simply to protect the areas from fire, and allow natural regeneration to produce secondary forest. This strategy will be most effective if remnant forest (i.e., seed sources) still exist in the landscape and soils have not been highly degraded. Patterns of forest recovery also suggest strategies for accelerating natural recovery by planting a suite of generalist species that are common in recently abandoned pastures in Puerto Rico and throughout much of the neotropics. [source]


Ecological Traits Predicting Amphibian Population Declines in Central America

CONSERVATION BIOLOGY, Issue 4 2003
Karen R. Lips
Populations of some species are extirpated, others have declined but survive, some have not obviously declined, and some are increasing. If amphibian populations at multiple sites were affected by the same factors, then surviving species should share traits that promote persistence, whereas declining species should share traits that promote susceptibility. Identifying these traits can help diagnose potential causes and thus help to direct conservation actions. Using logistic regression, we quantified the vulnerability of amphibian populations in four areas in Central America. We analyzed a species-specific database of taxonomic identity, geographic and elevational range, elevational distribution, adult and larval habitat, activity period, and maximum adult body size. We found that ( 1 ) all four sites exhibited the same pattern of decline ( there were no interactions between site and other variables ); ( 2 ) declining populations shared aquatic habitats, restricted elevational ranges, and large body sizes; and ( 3 ) there was an interaction between body size and elevational range. The most significant variable in the model was lifetime aquatic index, a factor unrelated to demographic vulnerability and one that therefore might indicate the potential causative agent( s ). Our results provide a predictive model with which to assess potential causes of population declines in other areas, and we generated a list of 52 species predicted to decline at a currently unaffected site in central Panama. Resumen: Las poblaciones de anfibios están declinando en todos los continentes donde ocurren, pero no todas las especies han sido afectadas por igual. Algunas especies han sido extirpadas, otras han declinado pero sobreviven, algunas no han declinado notablemente y otras están aumentando. Si las poblaciones de anfibios en varios sitios fueran afectadas por los mismos factores, las especies sobrevivientes deberían compartir características que promuevan la persistencia mientras que las especies en declinación deberían compartir características que promuevan la susceptibilidad. La identificación de estas características puede ayudar a diagnosticar las causas potenciales y así ayudar a dirigir medidas de conservación. Utilizando regresión logística, cuantificamos la vulnerabilidad de las poblaciones de anfibios en cuatro áreas de Centro América. Analizamos una base de datos de identidad taxonómica de especies, rango geográfico y altitudinal, distribución altitudinal, hábitat de larvas y adultos, período de actividad y máxima talla corporal de adultos. Encontramos que ( 1 ) los cuatro sitios presentaron el mismo patrón de declinación ( no hubo interacciones entre el sitio y otras variables ), ( 2 ) las poblaciones en declinación compartieron hábitats acuáticos, rangos altitudinales restringidos y tamaño corporal grande y ( 3 ) hubo interacción entre el tamaño corporal y el rango altitudinal. La variable más significativa del modelo fue el índice de vida acuática, un factor no relacionado con la vulnerabilidad demográfica y que, por lo tanto, podría indicar el agente causal potencial. Nuestros resultados proporcionan un modelo predictivo para evaluar las causas potenciales de declinación poblacional en otras áreas, y generamos una lista de 52 especies de declinación prevista en un sitio actualmente no afectado del centro de Panamá. [source]


Beta diversity of geometrid moths (Lepidoptera: Geometridae) in an Andean montane rainforest

DIVERSITY AND DISTRIBUTIONS, Issue 5 2003
Gunnar Brehm
Abstract. Turnover in species composition of the extremely species-rich family Geometridae (Lepidoptera) was investigated along an elevational gradient ranging from 1040 m to 2677 m above sea level. Moths were sampled using weak light traps (30 W) in three field periods in 1999 and 2000 in an Andean montane rainforest in the province of Zamora-Chinchipe in southern Ecuador. A total of 13 938 specimens representing 1010 species were analysed. Similarities of ensembles of all geometrid moths and of the subfamilies Ennominae and Larentiinae were calculated using the NESS index (with mmax). Ordinations performed using nonmetric multidimensional scaling (NMDS) and correspondence analysis depicted a gradual change of the ensembles along the altitudinal gradient. Extracted ordination scores significantly correlate with altitude (,0.97 , r , ,0.95, P < 0.001) and with ambient air temperature (0.93 , r , 0.97, P < 0.001). Temperature is therefore assumed to be the most important abiotic determinant responsible for the species turnover among the moths. Matrix correlation tests were performed in order to compare faunal matrices with matrices derived from available environmental factors. Both tree diversity and vegetation structure significantly correlate with faunal data, but tree diversity explains considerably more of the data variability (range: Mantel r = 0.81,0.83, P < 0.001) than vegetation structure (range: Mantel r = 0.35, P < 0.005 to r = 0.43, P < 0.001). Tree diversity also changes gradually and scores of the first NMDS dimension are highly significantly correlated with altitude (r = 0.98, P < 0.001). A common underlying factor such as ambient temperature might also be responsible for such vegetation changes. Additionally, simulated model data was developed that assumed a constant turnover of moth species and equal elevational ranges of all species involved. Despite the simplicity of the models, they fit empirical data very well (Mantel r > 0.80 and P < 0.001 in all models). [source]


Elevational gradients, area and tropical island diversity: an example from the palms of New Guinea

ECOGRAPHY, Issue 3 2004
Steven Bachman
The factors causing spatial variation in species richness remain poorly known. In this study, factors affecting species richness of palms (Palmae/Arecaceae) were studied along the elevational gradient of New Guinea. Interpolated elevational ranges were calculated from a database of all known collections for 145 species in 32 genera. The amount of land area at different elevations greatly affects the species richness gradient. If assessed in equal-elevation bands species richness appears to decline monotonically, but when assessed in equal-area bands species richness shows a pronounced mid-elevation peak, due to the large proportion of lowlands in New Guinea. By randomising species ranges within the total elevational gradient for palms and accounting for area, we found the mid-elevation peak to be consistent with a mid-domain effect caused by the upper and lower limits to palm distribution. Our study illustrates the importance of accounting for area in macroecological studies of richness gradients and introduces a novel yet simple method for doing this through the use of equal-area bands. Together, the effect of area and the mid-domain effect explain the majority of variation in species richness of New Guinea palms. We support calls for the multivariate assessment of the mid-domain effect on an equal footing with other potential explanations of species richness. [source]


TESTING THE ROLE OF INTERSPECIFIC COMPETITION IN THE EVOLUTIONARY ORIGIN OF ELEVATIONAL ZONATION: AN EXAMPLE WITH BUARREMON BRUSH-FINCHES (AVES, EMBERIZIDAE) IN THE NEOTROPICAL MOUNTAINS

EVOLUTION, Issue 5 2007
Carlos Daniel Cadena
Interspecific competition might drive the evolution of ecological niches and result in pairs of formerly competing species segregating along ecological gradients following a process of character displacement. This mechanism has been proposed to account for replacement of related species along gradients of elevation in many areas of the world, but the fundamental issue of whether competition is responsible for the origin of elevational replacements has not been tested. To test hypotheses about the role of interspecific competition in the origin of complementary elevational ranges, I combined molecular phylogenetics, phylogeography, and population genetic analyses on Buarremon torquatus and B. brunneinucha (Aves, Emberizidae), whose patterns of elevational distribution suggest character displacement or ecological release. The hypothesis that elevational distributions in these species changed in opposite directions as a result of competition is untenable because: (1) a historical expansion of the range of B. brunneinucha into areas occupied by B. torquatus was not accompanied by a shift in the elevational range of the former species; (2) when B. brunneinucha colonized the range of B. torquatus, lineages of the latter distributions had already diverged; and (3) historical trends in effective population size do not suggest populations with elevational ranges abutting those of putative competitors have declined as would be expected if competition caused range contractions. However, owing to uncertainty in coalescent estimates of historical population sizes, the hypothesis that some populations of B. torquatus have declined cannot be confidently rejected, which suggests asymmetric character displacement might have occurred. I suggest that the main role of competition in elevational zonation may be to act as a sorting mechanism that allows the coexistence along mountain slopes only of ecologically similar species that differ in elevational distributions prior to attaining sympatry. The contrasting biogeographic histories of B. brunneinucha and B. torquatus illustrate how present-day ecological interactions can have recent origins, and highlights important challenges for testing the hypothesis of character displacement in the absence of data on population history and robust reconstructions of the evolution of traits and geographic ranges. [source]


Range dynamics of small mammals along an elevational gradient over an 80-year interval

GLOBAL CHANGE BIOLOGY, Issue 11 2010
REBECCA J. ROWE
Abstract One expected response to observed global warming is an upslope shift of species elevational ranges. Here, we document changes in the elevational distributions of the small mammals within the Ruby Mountains in northeastern Nevada over an 80-year interval. We quantified range shifts by comparing distributional records from recent comprehensive field surveys (2006,2008) to earlier surveys (1927,1929) conducted at identical and nearby locations. Collector field notes from the historical surveys provided detailed trapping records and locality information, and museum specimens enabled confirmation of species' identifications. To ensure that observed shifts in range did not result from sampling bias, we employed a binomial likelihood model (introduced here) using likelihood ratios to calculate confidence intervals around observed range limits. Climate data indicate increases in both precipitation and summer maximum temperature between sampling periods. Increases in winter minimum temperatures were only evident at mid to high elevations. Consistent with predictions of change associated with climate warming, we document upslope range shifts for only two mesic-adapted species. In contrast, no xeric-adapted species expanded their ranges upslope. Rather, they showed either static distributions over time or downslope contraction or expansion. We attribute these unexpected findings to widespread land-use driven habitat change at lower elevations. Failure to account for land-use induced changes in both baseline assessments and in predicting shifts in species distributions may provide misleading objectives for conservation policies and management practices. [source]