scholarly journals Density of intertidal barnacles along their full elevational range of distribution conforms to the abundant-centre hypothesis

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6719 ◽  
Author(s):  
Ricardo A. Scrosati ◽  
Matthew J. Freeman
Keyword(s):  
Vertical Distribution ◽  
Environmental Gradients ◽  
Field Studies ◽  
Distribution Range ◽  
Sampling Effort ◽  
Predictive Tool ◽  
Distribution Centre ◽  
Substrate Properties ◽  
Elevational Range ◽  
High Elevations

The abundant-centre hypothesis (ACH) predicts that the density of a species should peak at its distribution centre and decrease similarly towards distribution margins. The ACH has been deduced from a theory that postulates that environmental conditions should be most favourable for a species at the centre of its distribution. This idealised density pattern, however, has been supported by limited field studies, as natural patterns are often more complex. It is thus of interest to examine under what conditions compliance with the ACH could be favoured. Such conditions could be smooth environmental gradients with limited habitat patchiness throughout the distribution range of a species. Thus, we tested the ACH by measuring the density of an intertidal barnacle (Semibalanus balanoides) across its full vertical distribution range (from low to high elevations) on a rocky shore with similar substrate properties across elevations. To do a reliable test, we surveyed eight elevation zones applying an equal sampling effort in each zone. Average barnacle density conformed to the ACH, as it peaked at the middle of the vertical distribution range of this species. The same underlying theory predicts a similar unimodal pattern for maximum body size, but this trait was decoupled from density, as maximum barnacle size increased from low to high elevations. Overall, although the ACH is not a universal predictive tool as once envisioned, it may predict some cases well, as shown by this study. Therefore, the ACH should not be discarded completely, and its domain of application should be further evaluated.

scholarly journals High turn-over rates at the upper range limit and elevational source-sink dynamics in a widespread songbird

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Martin U. Grüebler ◽  
Johann von Hirschheydt ◽  
Fränzi Korner-Nievergelt
Keyword(s):  
Environmental Gradients ◽  
Elevational Gradient ◽  
High Elevation ◽  
Range Limit ◽  
Apparent Survival ◽  
Breeding Sites ◽  
Mobile Species ◽  
Source Sink ◽  
Turn Over ◽  
High Elevations

AbstractThe formation of an upper distributional range limit for species breeding along mountain slopes is often based on environmental gradients resulting in changing demographic rates towards high elevations. However, we still lack an empirical understanding of how the interplay of demographic parameters forms the upper range limit in highly mobile species. Here, we study apparent survival and within-study area dispersal over a 700 m elevational gradient in barn swallows (Hirundo rustica) by using 15 years of capture-mark-recapture data. Annual apparent survival of adult breeding birds decreased while breeding dispersal probability of adult females, but not males increased towards the upper range limit. Individuals at high elevations dispersed to farms situated at elevations lower than would be expected by random dispersal. These results suggest higher turn-over rates of breeding individuals at high elevations, an elevational increase in immigration and thus, within-population source-sink dynamics between low and high elevations. The formation of the upper range limit therefore is based on preference for low-elevation breeding sites and immigration to high elevations. Thus, shifts of the upper range limit are not only affected by changes in the quality of high-elevation habitats but also by factors affecting the number of immigrants produced at low elevations.

scholarly journals Treeline ecotones shape the distribution of avian species richness and functional diversity in south temperate mountains

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Tomás A. Altamirano ◽  
Devin R. de Zwaan ◽  
José Tomás Ibarra ◽  
Scott Wilson ◽  
Kathy Martin
Keyword(s):  
Species Richness ◽  
Functional Diversity ◽  
Functional Traits ◽  
Habitat Structure ◽  
Environmental Gradients ◽  
Montane Forest ◽  
Avian Species ◽  
Point Counts ◽  
Mountain Habitats ◽  
Elevational Range

Abstract Mountains produce distinct environmental gradients that may constrain or facilitate both the presence of avian species and/or specific combinations of functional traits. We addressed species richness and functional diversity to understand the relative importance of habitat structure and elevation in shaping avian diversity patterns in the south temperate Andes, Chile. During 2010–2018, we conducted 2202 point-counts in four mountain habitats (successional montane forest, old-growth montane forest, subalpine, and alpine) from 211 to 1,768 m in elevation and assembled trait data associated with resource use for each species to estimate species richness and functional diversity and turnover. We detected 74 species. Alpine specialists included 16 species (22%) occurring only above treeline with a mean elevational range of 298 m, while bird communities below treeline (78%) occupied a mean elevational range of 1,081 m. Treeline was an inflection line, above which species composition changed by 91% and there was a greater turnover in functional traits (2–3 times greater than communities below treeline). Alpine birds were almost exclusively migratory, inhabiting a restricted elevational range, and breeding in rock cavities. We conclude that elevation and habitat heterogeneity structure avian trait distributions and community composition, with a diverse ecotonal sub-alpine and a distinct alpine community.

Studies on West African Forest Mosquitos

1949 ◽  
Vol 40 (3) ◽  
pp. 387-402 ◽  
Author(s):  
P. F. Mattingly
Keyword(s):  
Vertical Distribution ◽  
Field Studies ◽  
Abundant Species ◽  
Maximum Activity ◽  
General Level ◽  
Breeding Cycle ◽  
Level Of Activity ◽  
Relationship Of ◽  
The Vertical Distribution ◽  
Similar Kind

The present paper is the second of two dealing with field studies carried out near Lagos, Nigeria. The first paper covered four of the most abundant species encountered and the second is concerned with the remaining forty-eight. These are listed and the data relating to the thirty-eight least abundant, with the exception of two which were taken as males only, are given in tabular form. The other ten are dealt with at greater length. Males of twenty-six species were taken and in the case of three of these species they were so abundant as to create the impression that a swarming activity was involved. In the case of the ten more abundant species seasonal distribution curves are given based on average monthly catches and an attempt is made to relate these to variations in rainfall. The biting curves which are next discussed show a greater variety of types than those described in the first paper. In general, they are characterised by a fairly sharp peak associated with morning or evening twilight, but some have a more or less pronounced peak at both ends of the cycle and so correspond to the “eo-crepuscular” type of Haddow (1945). Anopheles paludis, like Taeniorhynchus africanus (described in the first paper) has an ill-defined period of maximum activity during the middle of the night. The necessity of sub-dividing the figures in order to obtain a picture of the vertical distribution of the various species led in one or two cases to anomalous results, but in general a clear and fairly convincing picture was obtained. None of the species dealt with in the present paper was sufficiently abundant to afford reliable data on hourly variations in vertical distribution. In the general discussion, which embodies such inferences as it has seemed permissible to draw from the data, attention is drawn to the fact that the so-called “biting cycle” does not, in all likelihood, depend exclusively on variations in the urge to bite, but is more probably an expression of cyclical changes taking place in the general level of activity of the mosquito. The possible relationship of such changes to changes of a similar kind in the physical environment is discussed, and it is pointed out that intrinsic rhythms in the mosquito, perhaps related to the breeding cycle, may also be involved. Some data are presented which, while partly explained by the presence of a sibling species, may also indicate an interrelationship between the breeding cycle and vertical distribution.

A taxonomic revision of Zamia montana and Zamia oligodonta, with notes on their conservation status

Phytotaxa ◽  
2015 ◽  
Vol 192 (4) ◽  
pp. 279
Author(s):  
Michael Calonje ◽  
GUSTAVO MORALES ◽  
CRISTINA LÓPEZ-GALLEGO ◽  
FRANCISCO JAVIER ROLDÁN
Keyword(s):  
Conservation Status ◽  
Taxonomic Revision ◽  
Field Studies ◽  
South American ◽  
South American Species ◽  
Western Cordillera ◽  
Morphological Differences ◽  
High Elevations

The taxonomy of Zamia montana and Z. oligodonta, two poorly understood species occurring at high elevations in the Western Cordillera of Colombia, is discussed. Zamia oligodonta was recently synonymized under Z. montana, but information derived from recent field studies is provided showing the two species are quite distinct. A treatment of both species is presented, including discussion of the major morphological differences between them and also between other South American species with prominently-veined leaflets. The conservation status of both species is evaluated.

scholarly journals The Within-Population Formation of the Upper Range Limit in a Songbird

2021 ◽  
Author(s):  
Martin Grüebler ◽  
Johann von Hirschheydt ◽  
Fränzi Korner-Nievergelt
Keyword(s):  
Environmental Gradients ◽  
Elevational Gradient ◽  
High Elevation ◽  
Range Limit ◽  
Apparent Survival ◽  
Breeding Sites ◽  
Factors Affecting ◽  
Mobile Species ◽  
Random Dispersal ◽  
High Elevations

Abstract The formation of the upper distributional range limit of species at mountain slopes is often based on environmental gradients resulting in changing demographic rates towards high elevations. However, we still lack an empiric understanding of how the interplay of demographic parameters forms the upper range limit in highly mobile species. Here, we study apparent survival and within-study area dispersal over a 700 m elevational gradient in barn swallows (Hirundo rustica) by using 15 years of capture-mark-recapture data. Annual apparent survival of adult breeding birds decreased while breeding dispersal probability of adult females, but not males increased towards the upper range limit. Individuals at high elevations dispersed to farms situated at lower elevations than would be expected by random dispersal. These results suggest higher turn-over rates of breeding individuals at high elevations, an elevational increase in immigration and thus, within-population source-sink dynamics between low and high elevations. The formation of the upper range limit therefore is based on preference for low-elevation breeding sites and immigration to high elevations. Thus, shifts of the upper range limit are not only affected by changes in the quality of high-elevation habitats but also by factors affecting the number of immigrants produced at low elevations.

scholarly journals Mixotrophy in nanoflagellates across environmental gradients in the ocean

2019 ◽  
Vol 116 (13) ◽  
pp. 6211-6220 ◽  
Author(s):  
Kyle F. Edwards
Keyword(s):  
Competitive Ability ◽  
Resource Competition ◽  
Environmental Gradients ◽  
Light Availability ◽  
Field Studies ◽  
Heterotrophic Nanoflagellates ◽  
Coastal Environments ◽  
Unicellular Eukaryotes ◽  
Theoretical Predictions ◽  
Trophic Strategy

Mixotrophy, the combination of autotrophic and heterotrophic nutrition, is a common trophic strategy among unicellular eukaryotes in the ocean. There are a number of hypotheses about the conditions that select for mixotrophy, and field studies have documented the prevalence of mixotrophy in a range of environments. However, there is currently little evidence for how mixotrophy varies across environmental gradients, and whether empirical patterns support theoretical predictions. Here I synthesize experiments that have quantified the abundance of phototrophic, mixotrophic, and heterotrophic nanoflagellates, to ask whether there are broad patterns in the prevalence of mixotrophy (relative to pure autotrophy and heterotrophy), and to ask whether observed patterns are consistent with a trait-based model of trophic strategies. The data suggest that mixotrophs increase in abundance at lower latitudes, while autotrophs and heterotrophs do not, and that this may be driven by increased light availability. Both mixotrophs and autotrophs increase greatly in productive coastal environments, while heterotrophs increase only slightly. These patterns are consistent with a model of resource competition in which nutrients and carbon can both limit growth and mixotrophs experience a trade-off in allocating biomass to phagotrophy vs. autotrophic functions. Importantly, mixotrophy is selected for under a range of conditions even when mixotrophs experience a penalty for using a generalist trophic strategy, due to the synergy between photosynthetically derived carbon and prey-derived nutrients. For this reason mixotrophy is favored relative to specialist strategies by increased irradiance, while at the same time increased nutrient supply increases the competitive ability of mixotrophs against heterotrophs.

scholarly journals New records of Limnonectes rhacodus (Inger, Boeadi and Taufik, 1996) (Lissamphibia: Anura: Dicroglossidae) from Sarawak, East Malaysia (Northwestern Borneo)

Check List ◽  
2013 ◽  
Vol 9 (6) ◽  
pp. 1588
Author(s):  
Pui Yong Min ◽  
Indraneil Das ◽  
Alexander Haas
Keyword(s):  
National Park ◽  
New Records ◽  
Distribution Range ◽  
East Malaysia ◽  
Elevational Range

We comment on the termination of the species nomen of Limnonectes rhacodus (originally described as Rana rhacoda) and report the species from two separate localities in Sarawak State, East Malaysia, based on individuals collected from Kubah National Park, Matang Range and Gunung Penrissen, Padawan, both in western Borneo. The species was previously known from central, western, and southern Kalimantan, Indonesia. These records are the first for Malaysia and extend the distribution range ca. 220 and 264 km northwest of the nearest locality of Bukit Baka-Bukit Raya National Park (West Kalimatan) and increase the species’ elevational range from 500 m to 1,120 m asl.

scholarly journals On the Vertical Distribution of the Light from Lighthouses Placed at High Elevations above the Sea-Level

Nature ◽  
1878 ◽  
Vol 19 (471) ◽  
pp. 19-20
Author(s):  
T. STEVENSON
Keyword(s):  
Vertical Distribution ◽  
Sea Level ◽  
High Elevations ◽  
The Vertical Distribution

scholarly journals Orobanche alba subsp. alba and subsp. major (Orobanchaceae) in Poland: current distribution, taxonomy, plant communities, hosts, and seed micromorphology

2012 ◽  
Vol 26 (1) ◽  
pp. 23-38 ◽  
Author(s):  
Renata Piwowarczyk
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Central Europe ◽  
Plant Communities ◽  
Current Distribution ◽  
Field Studies ◽  
Distribution Range ◽  
Seed Micromorphology ◽  
Critical Revision ◽  
Scanning Electron

Abstract The paper presents the current distribution of Orobanche alba subsp. major and subsp. alba in Poland, based on a critical revision of herbarium and literature data as well as results of my field studies. Most of their localities are in southeastern Poland: in the Małopolska Upland, Lublin Upland, Roztocze Hills, Polesie, Przemyśl Foothills (Pogórze Przemyskie), and Western Bieszczady Mts. These are the northernmost sites known for the species in Central Europe, so the new data extend its distribution range. Maps of distribution of both the subspecies in Poland and of subsp. major in Central Europe are included. Additionally, their seed micromorphology was compared using scanning electron microscopy (SEM). The taxonomy, biology, and ecology of both the subspecies of O. alba are also discussed.

scholarly journals Preliminary study on the diversity of Orthoptera from Kuala Belalong Field Studies Centre, Brunei Darussalam, Borneo

2018 ◽  
Vol 27 (2) ◽  
pp. 119-142 ◽  
Author(s):  
Ming Kai Tan ◽  
Rodzay bin Haji Abdul Wahab
Keyword(s):  
Southeast Asia ◽  
National Park ◽  
Field Studies ◽  
Field Trips ◽  
Sampling Effort ◽  
Species List ◽  
Dipterocarp Forest ◽  
Brunei Darussalam ◽  
History Of ◽  
Preliminary Study

The Orthoptera, comprising grasshoppers, crickets, and katydids, is diverse and species rich in tropical Southeast Asia, including the island of Borneo. However, not every part of Southeast Asia is equally well sampled and studied. This includes Brunei Darussalam, specifically at the Kuala Belalong Field Studies Centre (KBFSC) within the Ulu Temburong National Park. We present here an annotated and illustrated checklist of Orthoptera from the primary dipterocarp forest around Kuala Belalong based on three field trips in 2016 and 2017. We provide notes on their taxonomy (including how each species was identified) and natural history of species. In total, 72 species were recorded, representing eight of the 16 monophyletic orthopteran superfamilies. In total, 73.6% of all species recorded were singletons and doubletons, indicating that many species are probably rare. The collection led to the discovery of ten species new to science already published separately, with more expected to be described from pending material and confirmation. More species, including undescribed ones (at least four new species), are expected with continued sampling effort. Despite the 21 day-long surveying efforts from three trips around KBFSC, we believe that the species list provided here is non-exhaustive and only a preliminary one.

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