Geographic ranges of genera and their constituent species: structure, evolutionary dynamics, and extinction resistance

Paleobiology ◽  
2016 ◽  
Vol 42 (2) ◽  
pp. 269-288 ◽  
Author(s):  
Michael Foote ◽  
Kathleen A. Ritterbush ◽  
Arnold I. Miller
Keyword(s):  
Species Richness ◽  
Evolutionary Dynamics ◽  
Species Structure ◽  
Sampled Data ◽  
Widespread Species ◽  
Geographic Ranges ◽  
Number Of Species ◽  
Constituent Species ◽  
The Mean

AbstractWe explore the relationships among the geographic ranges of genera, the ranges and positions of their constituent species, and the number of species they contain, considering variation among coeval genera and changes within genera over time. Measuring range size as the maximal distance, or extent, between occurrences within a taxon, we find that the range of the most widespread species is a good predictor of the range of the genus, and that the number of species is a better predictor still. This analysis is complicated by a forced correlation: the range of a genus must be at least as large as that of each of its constituent species. We therefore focus on a second measure of range, the mean squared distance, or dispersion, of occurrences from the geographic centroid, which, by analogy to the analysis of variance, allows the total dispersion of a genus to be compared to the mean within-species dispersion and the dispersion among species centroids. We find that among-species dispersion is the principal determinant of genus dispersion. Within-species dispersion also plays a major role. The role of species richness is relatively small. Our results are not artifacts of temporal variation in the geographic breadth of sampled data. The relationship between changes in genus dispersion and changes in within- and among-species dispersion shows a symmetry, being similar in cases when the genus range is expanding and when it is contracting. We also show that genera with greater dispersion have greater extinction resistance, but that within- and among-species dispersion are not demonstrable predictors of survival once the dispersion of the genus is accounted for. Thus it is the range of the genus, rather than how it is attained, that is most relevant to its fate. Species richness is also a clear predictor of survival, beyond its effects on geographic range.

scholarly journals ГЕОГРАФІЧНА СТРУКТУРА УРБАНОФЛОР СТЕПОВОЇ ЗОНИ УКРАЇНИ

2016 ◽  
Vol 6 (2) ◽  
pp. 239-245
Author(s):  
G. G. Derevyanska ◽  
O. Z. Glukhov
Keyword(s):  
Great Influence ◽  
Steppe Zone ◽  
Significant Heterogeneity ◽  
Geographic Ranges ◽  
Urban Flora ◽  
Adventive Species ◽  
Number Of Species ◽  
The Impact ◽  
Transition Type

<p>This paper considers the problem of geographic links between the urban flora of steppe zone of Ukraine on the example of the industrial agglomeration Donetsk-Makeyevka, in comparison with urban flora of Kherson and Kirovograd. We presented the detailed description of special features of the composition of geographic elements of the agglomeration flora. It strongly reflects the characteristic features of steppe urban flora, because its territory is affected by the anthropogenic influence at large extend. The spectrum of geographic ranges of species from the agglomeration Donetsk-Makeyevka urban flora numbers 6 types, 12 classes and 130 groups of ranges. The urban flora is both represented by species with wide and local ranges, endemics, that point to its significant heterogeneity. However, compared to the flora of Kherson and Kirovograd, the role of holarctic type of ranges in the agglomeration flora (375 species compared to 400 and 522 species, respectively) is reduced in favor of the polyregional type, reflecting active adventization processes. The holarctic class itself is represented by 150 species (16.7%). It far exceeds the number of species of this class in the regional flora (9.2%), since nearly a half of their number in the observed flora is adventive species. Second place by the number of species in the holarctic class belongs to the European and North American group (13; 1.5%). Apart from this, seven more groups of the class, comprising 1-3 species each, are connected with North America. The polyregional type is represented to a large extent by the species of ruderal habitats. The total number of species of this type is 199. The palaearctic class includes the greatest number of ranges of species from the agglomeration urban flora (31); it consists of 175 species (19.5%), that is less than such index for regional flora (27.3%). The European and Old Mediterranean transition type comprises 97 species (10.8%), that is less than in other urban flora of steppe zone (128; 13.3% in Kherson and 171; 18.0% in Kirovograd). The Nomadic type numbers 132 species (14.7%). One more species – Verbascum marschallianum Ivanina et Tzvelev – is related to the Nomadic and European transition type. The Nomadic and Old Mediterranean transition type includes 93 species (10.4%). This all suggests heterogeneity of urban flora of steppe zone of Ukraine due to their wide geographic connections. On the one hand, they have features of regional flora, which was formed under the great influence of Old Mediterranean flora and has a significant number of narrow-range and endemic species. On the other hand, under the impact of urbanization one can observe the reduction of the role of ranges of the Nomadic type and the enhanced role of the polyregional type due to the significant number of adventive species.</p><p> </p>

Species structure in Zambian miombo woodland

1987 ◽  
Vol 3 (2) ◽  
pp. 109-118 ◽  
Author(s):  
E. N. Chidumayo
Keyword(s):  
Species Diversity ◽  
Biological Diversity ◽  
Diversity Index ◽  
Species Density ◽  
Species Structure ◽  
Miombo Woodland ◽  
Species Diversity Index ◽  
Old Growth ◽  
Number Of Species ◽  
The Mean

ABSTRACTMiombo woodland in Zambia is divided into wetter and drier types by the 1100 mm mean rainfall isohyet. In the present study two wetter (Northern, Northwestern) and three drier (Central, Eastern, Western) miombo subtypes were recognized.A survey of the woody flora of 94 old-growth and 58 coppice stands in the five miombo subtypes revealed some significant differences in species diversity among them. The floristic differentiantion of miombo subtypes was best achieved by the use of the Shannon species diversity index (H′) and species density (number of species 0.1 ha−1 or 0.4 ha−1). H′ in miombo decreased from 2.247 in Northwestern to 2.136 in Northern, 2.052 in Eastern, 1.918 in Central and 1.824 in Western subtypes. Although species density was not significantly different between wetter miombo subtypes, this decreased in a similar fashion from 18.78 0.1 ha−1 in Northwestern to 18.30 in Northern, 16.65 in Eastern, 14.79 in Central and 12.29 in Western subtypes. The low species diversity in Western drier miombo was attributed to the combined effects of low soil fertility and rainfall.Although the mean number of species per 0.1 ha plot was higher in coppice samples, species richness (d) and index of diversity (H′) were lower than in old-growth samples. These results indicate lower species diversity in regenerating miombo. The dynamic aspects of species structure should therefore be considered in the future conservation of biological diversity in miombo woodland.

scholarly journals The role of migration in mutant evolution in fragmented populations

2021 ◽  
Author(s):  
Jesse Kreger ◽  
Donovan Brown ◽  
Natalia Komarova ◽  
Dominik Wodarz ◽  
Justin Pritchard
Keyword(s):  
Migration Rate ◽  
Evolutionary Biology ◽  
Evolutionary Dynamics ◽  
Hematopoietic Stem ◽  
Fragmented Populations ◽  
Colonic Crypts ◽  
Hematopoietic Stem Cell Niches ◽  
The Mean ◽  
Clonal Composition

Mutant evolution in fragmented populations has been studied extensively in evolutionary biology. With an increased focus on evolutionary dynamics in medical research, quantification of mutant load in fragmented populations with varying levels of migration has become especially important. Examples of fragmented populations are hematopoietic stem cell niches in the bone marrow where cells can re-circulate between niches through the blood, or colonic crypts where movement of cells across different crypts is not thought to be common. Here we use a combination of experiments and theory to investigate the role of migration in mutant distribution. In the case of neutral mutants, the experiments confirmed that while the mean number of mutants is not influenced by migration, the probability distribution is, which manifested itself in a change in the skewedness of the distribution of the mutant numbers in the demes. In the case of disadvantageous mutants, we investigated the phenomenon of the increase in the expected number of mutants compared to that of the selection-mutation balance. In a single deme, this increase is observed when the deme size is lower than the critical size, $N_c$. In a fragmented system that consists of connected demes with a probability of migration, the increase in mutant numbers above the selection-mutation balance can be maintained in small ($N<N_c$) demes as long as the migration rate is sufficiently small. The migration rate above which the mutants approach the selection-mutation balance decays exponentially with $N/N_c$. These findings are relevant in the context of the complex and poorly understood processes that may lead to changes in the clonal composition in tissues and tumors.

The role of positive and negative interspecific associations in the organization of communities of intestinal helminths of bats

Parasitology ◽  
1991 ◽  
Vol 103 (1) ◽  
pp. 127-138 ◽  
Author(s):  
J. M. Lotz ◽  
W. F. Font
Keyword(s):  
Species Richness ◽  
Frequency Distribution ◽  
Host Population ◽  
Helminth Species ◽  
Positive Interactions ◽  
Intestinal Helminth ◽  
Number Of Species ◽  
Interspecific Associations ◽  
Species Pairs ◽  
The Mean

Twelve populations of bats were examined to determine the extent of interspecific associations in determining the species richness of intestinal helminth infracommunities. The pool of helminth species which was available to individual bats ranged from 2 to 21. The ‘summed binomial’ distribution was determined to underlie the host frequency distribution of the number of helminth species per host. Overall covariation in occurrences of species in replicated communities can be detected by testing for the equality of the observed variance of the host frequency distribution to the variance expected when species are allocated to hosts at random. Where statistically significant the covariance was indicative of a majority of positive rather than negative interspecific associations. As the mean number of species per host in a host population increases not only does the number of positive associations increase but so does the proportion of species pairs which exhibit positive associations. Although there is an increase in the proportion of species pairs which exhibit positive associations as the number of species increases, the magnitude of the associations (as indicated by the mean positive or the mean negative pairwise covariances) does not. Therefore, we concluded that positive interactions are more common than negative interactions in determining the species richness of helminth infracommunities of bats. Further, positive associations become even more important as the community becomes more complex. However, the increased importance is derived from the number rather than the strength of the associations.

scholarly journals Breeding bird communities in a morain landscape (Affi, North-Western Venetia): a preliminary survey.

2012 ◽  
Vol 81 (2) ◽  
Author(s):  
Corrado Battisti ◽  
Giuseppe Dodaro
Keyword(s):  
Species Richness ◽  
Diversity Index ◽  
Research Effort ◽  
Absolute Number ◽  
Bird Communities ◽  
Breeding Bird ◽  
Number Of Species ◽  
The Mean ◽  
High Level ◽  
River Plain

A pilot study was conducted on a moraine hilly landscape (Affi, Verona). We found 43 species of birds overall (40 breeding, two migrants, one exotic species). Mosaics showed the largest absolute number of species (n = 25), the higher mean species richness and the highest diversity index. The croplands and wood fragments, on the contrary, pointed out the lowest absolute number of species, the vineyards showed the mean species richness. These bird communities are typical of conditions with high heterogeneity (mosaic environment) to medium-high level of anthropization, with a species composition characterized by the dominance of common and widespread taxa. We observed individuals of Ptyonoprogne rupestris in atypical environments (anthropized river plain). A stronger research effort is necessary in order to complete the knowledge of breeding bird communities in these particular environments.

Long-term dynamics and destruction of marsh vegetation in the Kolokolkova Bay of the Barents Sea

2012 ◽  
pp. 66-77 ◽  
Author(s):  
I. A. Lavrinenko ◽  
O. V. Lavrinenko ◽  
D. V. Dobrynin
Keyword(s):  
Species Composition ◽  
Plant Communities ◽  
Barents Sea ◽  
Mean Value ◽  
Marsh Vegetation ◽  
Composition And Structure ◽  
The Mean ◽  
Species Composition And Structure

The satellite images show that the area of marshes in the Kolokolkova bay was notstable during the period from 1973 up to 2011. Until 2010 it varied from 357 to 636 ha. After a severe storm happened on July 24–25, 2010 the total area of marshes was reduced up to 43–50 ha. The mean value of NDVI for studied marshes, reflecting the green biomass, varied from 0.13 to 0.32 before the storm in 2010, after the storm the NDVI decreased to 0.10, in 2011 — 0.03. A comparative analysis of species composition and structure of plant communities described in 2002 and 2011, allowed to evaluate the vegetation changes of marshes of the different topographic levels. They are fol­lowing: a total destruction of plant communities of the ass. Puccinellietum phryganodis and ass. Caricetum subspathaceae on low and middle marches; increasing role of halophytic species in plant communities of the ass. Caricetum glareosae vic. Calamagrostis deschampsioides subass. typicum on middle marches; some changes in species composition and structure of plant communities of the ass. Caricetum glareosae vic. Calamagrostis deschampsioides subass. festucetosum rubrae on high marches and ass. Parnassio palustris–Salicetum reptantis in transition zone between marches and tundra without changes of their syntaxonomy; a death of moss cover in plant communities of the ass. Caricetum mackenziei var. Warnstorfia exannulata on brackish coastal bogs. The possible reasons of dramatic vegetation dynamics are discussed. The dating of the storm makes it possible to observe the directions and rates of the succession of marches vegetation.

Seasonal trends in the stable isotopic composition of snow and meltwater runoff in a subarctic catchment at Okstindan, Norway

2004 ◽  
Vol 35 (2) ◽  
pp. 119-137 ◽  
Author(s):  
S.D. Gurney ◽  
D.S.L. Lawrence
Keyword(s):  
Isotopic Composition ◽  
Mean Value ◽  
Mean Values ◽  
Stable Isotopic Composition ◽  
Meltwater Runoff ◽  
Stable Isotopic ◽  
The Mean ◽  
The Difference ◽  
Δ18o And Δd

Seasonal variations in the stable isotopic composition of snow and meltwater were investigated in a sub-arctic, mountainous, but non-glacial, catchment at Okstindan in northern Norway based on analyses of δ18O and δD. Samples were collected during four field periods (August 1998; April 1999; June 1999 and August 1999) at three sites lying on an altitudinal transect (740–970 m a.s.l.). Snowpack data display an increase in the mean values of δ18O (increasing from a mean value of −13.51 to −11.49‰ between April and August), as well as a decrease in variability through the melt period. Comparison with a regional meteoric water line indicates that the slope of the δ18O–δD line for the snowpacks decreases over the same period, dropping from 7.49 to approximately 6.2.This change points to the role of evaporation in snowpack ablation and is confirmed by the vertical profile of deuterium excess. Snowpack seepage data, although limited, also suggest reduced values of δD, as might be associated with local evaporation during meltwater generation. In general, meltwaters were depleted in δ18O relative to the source snowpack at the peak of the melt (June), but later in the year (August) the difference between the two was not statistically significant. The diurnal pattern of isotopic composition indicates that the most depleted meltwaters coincide with the peak in temperature and, hence, meltwater production.

scholarly journals Forensic Investigation of Four Monitored Green Infrastructure Inlets

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1787
Author(s):  
Leena J. Shevade ◽  
Franco A. Montalto
Keyword(s):  
Measurement Uncertainty ◽  
Green Infrastructure ◽  
Stormwater Management ◽  
Catchment Area ◽  
Low Flow ◽  
Inflow Rate ◽  
Forensic Investigation ◽  
Flow Conditions ◽  
The Mean

Green infrastructure (GI) is viewed as a sustainable approach to stormwater management that is being rapidly implemented, outpacing the ability of researchers to compare the effectiveness of alternate design configurations. This paper investigated inflow data collected at four GI inlets. The performance of these four GI inlets, all of which were engineered with the same inlet lengths and shapes, was evaluated through field monitoring. A forensic interpretation of the observed inlet performance was conducted using conclusions regarding the role of inlet clogging and inflow rate as described in the previously published work. The mean inlet efficiency (meanPE), which represents the percentage of tributary area runoff that enters the inlet was 65% for the Nashville inlet, while at Happyland the NW inlet averaged 30%, the SW inlet 25%, and the SE inlet 10%, considering all recorded events during the monitoring periods. The analysis suggests that inlet clogging was the main reason for lower inlet efficiency at the SW and NW inlets, while for the SE inlet, performance was compromised by a reverse cross slope of the street. Spatial variability of rainfall, measurement uncertainty, uncertain tributary catchment area, and inlet depression characteristics are also correlated with inlet PE. The research suggests that placement of monitoring sensors should consider low flow conditions and a strategy to measure them. Additional research on the role of various maintenance protocols in inlet hydraulics is recommended.

scholarly journals Landscape resistance constrains hybridization across contact zones in a reproductively and morphologically polymorphic salamander

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Guillermo Velo-Antón ◽  
André Lourenço ◽  
Pedro Galán ◽  
Alfredo Nicieza ◽  
Pedro Tarroso
Keyword(s):  
Contact Zone ◽  
Environmental Heterogeneity ◽  
Evolutionary Dynamics ◽  
Morphological Differentiation ◽  
Phenotypic Traits ◽  
Hybrid Zones ◽  
Landscape Resistance ◽  
Phenotypic Differentiation ◽  
Contact Zones

AbstractExplicitly accounting for phenotypic differentiation together with environmental heterogeneity is crucial to understand the evolutionary dynamics in hybrid zones. Species showing intra-specific variation in phenotypic traits that meet across environmentally heterogeneous regions constitute excellent natural settings to study the role of phenotypic differentiation and environmental factors in shaping the spatial extent and patterns of admixture in hybrid zones. We studied three environmentally distinct contact zones where morphologically and reproductively divergent subspecies of Salamandra salamandra co-occur: the pueriparous S. s. bernardezi that is mostly parapatric to its three larviparous subspecies neighbours. We used a landscape genetics framework to: (i) characterise the spatial location and extent of each contact zone; (ii) assess patterns of introgression and hybridization between subspecies pairs; and (iii) examine the role of environmental heterogeneity in the evolutionary dynamics of hybrid zones. We found high levels of introgression between parity modes, and between distinct phenotypes, thus demonstrating the evolution to pueriparity alone or morphological differentiation do not lead to reproductive isolation between these highly divergent S. salamandra morphotypes. However, we detected substantial variation in patterns of hybridization across contact zones, being lower in the contact zone located on a topographically complex area. We highlight the importance of accounting for spatial environmental heterogeneity when studying evolutionary dynamics of hybrid zones.

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