Are characteristics of introduced salmonid fishes biased by propagule pressure?

2005 ◽  
Vol 62 (4) ◽  
pp. 950-959 ◽  
Author(s):  
Robert I Colautti
Keyword(s):  
Life History ◽  
Statistical Models ◽  
Propagule Pressure ◽  
Morphological Characteristics ◽  
Ecological Factors ◽  
Salmonid Fishes ◽  
Salmonid Species ◽  
Species Characteristics ◽  
Contrast Group ◽  
Latitudinal Range

Many recent studies of nonindigenous species (NIS) have used life history and morphological characteristics of invaders to either (i) build statistical models that predict new invaders or (ii) test ecological and evolutionary hypotheses. However, species characteristics may be confounded if NIS are transported or introduced nonrandomly with respect to the chosen contrast group, which typically consists of native or globally available species. For example, deliberately introduced NIS are often chosen according to economic rather than ecological factors. Here, I use stocking records of salmonid species introduced into Nevada, USA, to test for propagule biases within this system. I find that established salmonids are introduced significantly more times, and in greater numbers, than are those that fail and that species chosen for introduction are a nonrandom sample of the global salmonid species pool. Statistical differences among characteristics of salmonid species that established, those that were introduced, and those from the global source pool suggest that maximum reported size and weight as well as latitudinal range and midlatitude all represent propagule-biased characteristics of salmonids introduced into Nevada. These results highlight the need for caution when using characteristics of invaders to develop statistical models or to test hypotheses relevant to ecology and evolution.

Evidence of long and discontinuous juvenile periods in Trillium catesbaei under contrasting levels of herbivory

Botany ◽  
2014 ◽  
Vol 92 (1) ◽  
pp. 77-81 ◽  
Author(s):  
Christopher R. Webster ◽  
Michael A. Jenkins
Keyword(s):  
Life History ◽  
Reproductive Success ◽  
Age Structure ◽  
Morphological Characteristics ◽  
Population Viability ◽  
Plant Age ◽  
Life History Stage ◽  
Structure And Morphology ◽  
Single Leaf ◽  
Poor Indicator

We investigated the influence of chronic herbivory by white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)) on the age structure and morphology of Trillium catesbaei Elliott. At sites with contrasting histories of deer abundance (Cades Cove, high; Whiteoak Sink, low), we measured morphological characteristics and determined minimum plant age for 60 plants (30 per site) in the single-leaf life-history stage. We chose this stage because its presence is considered an indication of successful reproduction by the previous generation, but its value could be inflated if plants regress or remain in this stage for extended periods. Our results suggest that T. catesbaei may spend upwards of a decade in this stage. Cades Cove single leaves were significantly older (p = 0.011) than those at Whiteoak Sink. Rhizome recession (decay of the oldest portion) was more common at Cades Cove, suggesting greater regression to this stage from three-leaf stages. Although minimum plant age was significantly associated with vegetative attributes (p < 0.002) at Whiteoak Sink, these attributes were decoupled at Cades Cove (p ≥ 0.642). Collectively, our results suggest that chronic herbivory may lead to a long and regressive residency period in the single-leaf stage. Consequently, in Trillium populations heavily impacted by deer, the number of single-leaf plants may be a poor indicator of reproductive success and population viability.

Brain size evolution in anurans: a review

2019 ◽  
Vol 69 (3) ◽  
pp. 265-279 ◽  
Author(s):  
Chun Lan Mai ◽  
Wen Bo Liao
Keyword(s):  
Sexual Selection ◽  
Life History ◽  
Life History Traits ◽  
Developmental Stages ◽  
Brain Size ◽  
Ecological Factors ◽  
Brain Regions ◽  
Sperm Length ◽  
Testis Size ◽  
Size Evolution

Abstract Selection pressure is an important force in shaping the evolution of vertebrate brain size among populations within species as well as between species. The evolution of brain size is tightly linked to natural and sexual selection, and life-history traits. In particular, increased environmental stress, intensity of sexual selection, and slower life history usually result in enlarged brains. However, although previous studies have addressed the causes of brain size evolution, no systematic reviews have been conducted to explain brain size in anurans. Here, we review whether brain size evolution supports the cognitive buffer hypothesis (CBH), the expensive tissue hypothesis (ETH), or the developmental cost hypothesis (DCH) by analyzing the intraspecific and/or interspecific patterns in brain size and brain regions (i.e., olfactory nerves, olfactory bulbs, telencephalon, optic tectum, and cerebellum) associated with ecological factors (habitat, diet and predator risk), sexual selection intensity, life-history traits (age at sexual maturity, mean age, longevity, clutch size and egg size, testis size and sperm length), and other energetic organs. Our findings suggest that brain size evolution in anurans supports the CBH, ETH or DCH. We also suggest future directions for studying the relationships between brain size evolution and crypsis (i.e., ordinary mucous glands in the skin), and food alteration in different developmental stages.

scholarly journals Distributional range, ecology, and mating system of the Cape mole-rat (Georychus capensis) family Bathyergidae

2017 ◽  
Vol 95 (10) ◽  
pp. 713-726 ◽  
Author(s):  
J.H. Visser ◽  
N.C. Bennett ◽  
B. Jansen van Vuuren
Keyword(s):  
Life History ◽  
Mating System ◽  
Vegetation Type ◽  
Ecological Factors ◽  
Disjunct Distribution ◽  
Testis Size ◽  
Extrinsic Factors ◽  
Mole Rat ◽  
Testicular Size ◽  
Life History Patterns

Interpopulation variation in life-history patterns are influenced by intrinsic and extrinsic factors. Life-history patterns have been intensely studied in the eusocial African bathyergid species, largely neglecting the solitary species. Of these solitary genera, the Cape mole-rat (Georychus capensis (Pallas, 1778)) is endemic to South Africa with a disjunct distribution across its range. Knowledge regarding this species is rudimentary; therefore, this study aimed to investigate the current distribution of the species with particular attention to common ecological variables, differences in body size between localities and sexes, as well as its reproduction and mating system. Georychus is a habitat specialist restricted to specific ecological areas. A lack of sexual size dimorphism and correlation between male testis size and number of females in the population, suggests a polygynous mating system, facilitated by the spatial distribution of the sexes. A positive relationship between male testes size and percentage of females in populations sampled suggests that larger sperm reserves (i.e., larger testes) are required in populations with a higher percentage of females. In addition, mating variables (testicular size and litter size) are linked to ecological factors (elevation, aridity, soil type, and vegetation type) that could impact mate searching, mating success, and food resources.

MORPHOLOGY OF LARVAE, DEUTONYMPHS, AND ADULTS OF THE WATER MITE NAJADICOLA INGENS (PROSTIGMATA: PARASITENGONA: HYGROBATOIDEA) WITH REMARKS ON PHYLOGENETIC RELATIONSHIPS AND REVISION OF TAXONOMIC PLACEMENT OF NAJADICOLINAE

1984 ◽  
Vol 116 (5) ◽  
pp. 691-701 ◽  
Author(s):  
Thomas W. Simmons ◽  
Ian M. Smith
Keyword(s):  
Life History ◽  
Phylogenetic Relationship ◽  
Phylogenetic Relationships ◽  
Morphological Characteristics ◽  
Water Mite ◽  
History Information ◽  
Relationship Of ◽  
First Time

AbstractAdults and deutonymphs of Najadicola ingens (Koenike) are redescribed and larvae are described for the first time. In light of larval, deutonymphal and adult character states, the phylogenetic relationship of Najadicola with genera in the families Pionidae and Unionicolidae is re-evaluated and transfer of the subfamily Najadicolinae to Pionidae is proposed. Original life history information is presented to supplement existing literature. Parasitism by larval N. ingens on an adult chironomid of the genus Polypedilum is reported. The unique behavioural and morphological characteristics of members of Najadicola suggest that mussel parasitism evolved independently from a parallel adaptive sequence in the genus Unionicola.

Some Observations on the Biology and the Ecology of a Venus Striatula Population in the Bay of Douarnenez, Brittany

1985 ◽  
Vol 65 (4) ◽  
pp. 889-900 ◽  
Author(s):  
J. Guillou ◽  
P. G. Sauriau
Keyword(s):  
Shallow Water ◽  
Black Sea ◽  
Environmental Conditions ◽  
Ecological Factors ◽  
Fine Sand ◽  
The Black Sea ◽  
High Exposure ◽  
Lofoten Islands ◽  
Muddy Sediments ◽  
Latitudinal Range

INTRODUCTIONVenus striatula (da Costa) (= Venus gallina L.) occurs in high densities in shallow water on a bottom of clean fine sand in the Bay of Douarnenez. The environmental conditions are characterized by an obvious sediment instability due to a high exposure to westerly swells (Guillou & Le Moal, 1978). This species is preferentially distributed in the fine sands (Petersen, 1913; Thorson, 1957), but is relatively tolerant towards certain ecological factors and so is sometimes found in very muddy sediments. It also shows an extended latitudinal range, since it is recorded from the Lofoten Islands to the Canaries, in the Mediterranean and the Black Sea (Tebble, 1966).

scholarly journals Multi-scale environmental filters and niche partitioning govern the distributions of riparian vegetation guilds

2014 ◽  
Author(s):  
Nate W Hough-Snee ◽  
Brian Laub ◽  
David M. Merritt ◽  
A. Lexine Long ◽  
Lloyd L. Nackley ◽  
...  
Keyword(s):  
Life History ◽  
Regional Climate ◽  
Morphological Characteristics ◽  
Species Traits ◽  
Life History Strategies ◽  
Rooting Depth ◽  
Environmental Filters ◽  
Support Tool ◽  
Channel Form ◽  
Riparian Plant

Across landscapes, riparian plant communities assemble under varying levels of disturbance, environmental stress, and resource availability, leading to the development of distinct riparian life-history guilds. Identifying the environmental filters that exert selective pressures and favor specific vegetation guilds within riverscapes is a critical step in setting baseline expectations for how riparia may respond to the environmental conditions anticipated under future global change scenarios. In this study, we ask (1) what functional riparian plant guilds exist across two major North American river basins? (2) What environmental filters shape riparian guild distributions? (3) Does resource partitioning between guilds influence guild distributions and co-occurrence? We identified riparian plant guilds, examining relationships between regional climate and watershed hydrogeomorphic characteristics, stream channel form, and co-occurring riparian guilds. Woody species composition was measured at 703 streams and each species’ traits were extracted from a database in five functional areas: life form, persistence and growth, reproduction, and resource use. We clustered species into guilds by morphological characteristics and attributes related to environmental tolerances, modeling guild distributions as a product of environmental filters (stressors and resources) and guild co-existence. We identified five guilds, i) a tall, deeply rooted, long-lived, evergreen tree guild, ii) a xeric disturbance tolerant shrub guild, iii) a hydrophytic, thicket-forming shrub guild, iv) a low-statured, shade-tolerant, understory shrub guild and v) a flood tolerant, mesoriparian shrub guild. Guilds were most strongly discriminated by one another species’ rooting depth, canopy height and potential to resprout and grow following biomass-removing disturbance. Hydro-climatic variables including precipitation, watershed area, water table depth, and channel form attributes reflective of hydrologic regime were predictors of guilds whose life history strategies had affinity or aversion to flooding, drought, and fluvial disturbance. Biotic interactions excluded guilds with divergent life history strategies and/or allowed for the co-occurrence of guilds that partition resources differently in the same environment. We conclude that riparian guilding provides a useful framework for assessing how disturbance and bioclimatic gradients shape riparian functional plant diversity. Multiple processes should be considered when the riparian response guilds framework is to be used as a land-use decision-support tool framework

scholarly journals Climatic and anthropogenic factors affect Ailanthus altissima invasion in a Mediterranean region

Plant Ecology ◽  
2021 ◽  
Author(s):  
Riccardo Motti ◽  
Maurizio Zotti ◽  
Giuliano Bonanomi ◽  
Alessia Cozzolino ◽  
Adriano Stinca ◽  
...  
Keyword(s):  
Land Use ◽  
Propagule Pressure ◽  
Ecological Factors ◽  
Mediterranean Ecosystems ◽  
High Elevation ◽  
Climatic Conditions ◽  
Anthropogenic Factors ◽  
Ailanthus Altissima ◽  
Poor Correlation ◽  
Mean Annual Temperature

AbstractAilanthus altissima is an aggressive invasive tree worldwide, but the ecological factors that lead to the spread of this species in Mediterranean ecosystems are still unclear. Here we aim to identify such factors, focusing on the interaction of human activity with climatic conditions. We determined the occurrence and abundance of Ailanthus in 240 sites and studied their relationship with 20 variables representing climatic, geographic, and topographic factors, as well as land use, in the region of Campania (southern Italy). Overall, we found that temperature and rainfall in Campania are suitable for Ailanthus, with the only major constraint being the temperature at an altitude exceeding 900 m a.s.l.. We found that Ailanthus is unable to spread where the mean annual temperature is lower than 11.1 °C. By contrast, precipitation variables showed poor correlation with Ailanthus distribution, suggesting that rainfall in the selected study sites is suitable to sustain the growth of this tree. About land use variables, roads were the primary landscape feature along which this species spread and invaded new areas. Roads probably combine high propagule pressure and favorable growing conditions in terms of available resources i.e., light, water, and mineral nutrients, that allow Ailanthus to establish and spread along roadside edges in different ecosystems. In conclusion, we found that climate and human-associated variables are correlated with the current occurrence of Ailanthus, with the temperature being more influential at high elevation sites and road distance playing a prominent role in low elevation areas.

scholarly journals Inconsistencies among secondary sources of chukar partridge (Alectoris chukar) introductions to the United States

2015 ◽  
Author(s):  
Michael P Moulton ◽  
Wendell P Cropper, Jr ◽  
Andrew J Broz
Keyword(s):  
Propagule Pressure ◽  
Bird Species ◽  
The United States ◽  
Establishment Success ◽  
Secondary Sources ◽  
Alectoris Chukar ◽  
Large Numbers ◽  
The Usa ◽  
Species Characteristics ◽  
Chukar Partridge

An important source of information concerning the fates of intentionally introduced exotic bird species has been collections of historical data that sometimes include species released, numbers released, locations of release, and establishment success. These data have been used to assess potential predictors of establishment success such as propagule pressure, site-level factors, and species characteristics. In order to better understand the limitations of such historical compilations, we compared data for the Chukar (Alectoris chukar) introductions to the USA from two often used compilations and from other sources associated with Chukar introduction programs. We found the major compilations of Long (1981) and Lever (1987) are inconsistent and likely to be incomplete, and inaccurate, in terms of the taxa introduced, the numbers introduced, and the fates of these introductions. Propagule pressure analyses have often assumed that every bird in every release must be summed to represent the propagule pressure necessary for establishment. We found, however, that large numbers of birds were released into states and counties with already established populations. Additionally, in numerous states very large numbers of Chukars were unsuccessfully released. We conclude that site-level factors were more important influences of establishment success than propagule pressure was.

scholarly journals Morphological Divergence of Hermann’s Tortoise (Testudo hermanni boettgeri) in Albania

2020 ◽  
Author(s):  
Sokol Duro ◽  
Bektas Sönmez ◽  
Ozan Gündemir ◽  
Tefik Jashari ◽  
Tomasz Szara
Keyword(s):  
Body Size ◽  
Carapace Length ◽  
Morphological Characteristics ◽  
Ecological Factors ◽  
The Body ◽  
Local Conditions ◽  
Geographical Regions ◽  
Testudo Hermanni ◽  
Different Populations ◽  
Morphological Differences

Testudines show phenotypic plasticity, and variation among specific populations within a species is widespread. Morphological differences between populations reflect ecological factors that drive adaptation to local conditions. In this context, gathered basic data on morphology of the Hermann&rsquo;s tortoise (Testudo hermanni boettgeri) to document their variation across different geographical regions. We surveyed Hermann&rsquo;s tortoises, in five different locales within Albania during April and May 2020 and measured 20 morphological characteristics, including carapace and plastron dimensions. We measured 188 tortoises (81 males, 107 females) in this study, and females were larger (P=.0001) and heavier (P=.0001) than males. Mean straight carapace length [SCL] and body mass were = 172.4 mm and 1128.8 g, respectively, for females and 151.3 mm and 735 g, respectively, for males. The overall Albanian T. h. boettgeri population were regionally diverged into 3 different populations that were situated in northern (Shkodra), central (Tirana, Berati and Ballshi) and southern (Saranda) Albania. The body size (curved carapace length; CCL) of females was positively correlated (r=0.216; P=0.025) with the latitude degree, in accordance with Bergmann's rule. However, there was no correlation between body size and degrees north latitude in males. These striking regional differences among Albanian T. h. boettgeri strongly suggest that further study of molecular variations in and reproductive output of Hermann&rsquo;s tortoises is warranted.

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