scholarly journals Variation in the population biology of protogynous coral reef fishes over tens of kilometres

2004 ◽  
Vol 61 (2) ◽  
pp. 205-218 ◽  
Author(s):  
Nick Gust
Keyword(s):  
Population Biology ◽  
Life Histories ◽  
Spatial Scales ◽  
Reef Fishes ◽  
Sex Reversal ◽  
Outer Shelf ◽  
Terminal Phase ◽  
Local Populations ◽  
Sexual Composition ◽  
And Shifts

This study describes changes in the timing of maturation and sex reversal and shifts in the sexual composition of unfished local populations of protogynous reef fishes across the continental shelf of the Great Barrier Reef. On outer shelf reef crests, both Chlorurus sordidus and Scarus frenatus matured as females and underwent protogynous sex reversal at reduced sizes and ages relative to fish from equivalent midshelf habitats 20 km away. Earlier maturation at smaller body sizes on the outer shelf is likely to be an adaptive response to the higher mortality rates in these habitats compared with the middle shelf. Furthermore, reduced size and age at sex reversal on the outer shelf is consistent with the reduced growth and increased mortality regimes in these locations. The sexual composition of local populations changed markedly across the shelf for C. sordidus but not for S. frenatus. High densities of C. sordidus on the outer shelf were characterized by threefold higher proportions of both terminal-phase and primary males than on midshelf reefs. Differences between local populations separated by tens of kilometres highlight the danger of assuming homogeneous sexual compositions and life histories when managing exploited reef fishes over larger spatial scales.

scholarly journals Parasites—the new frontier: celebrating Darwin 200

2009 ◽  
Vol 5 (5) ◽  
pp. 625-627 ◽  
Author(s):  
Paul Schmid-Hempel
Keyword(s):  
Population Biology ◽  
Life Histories ◽  
Evolutionary Ecology ◽  
Adaptive Value ◽  
Wide Range ◽  
New Frontier ◽  
Underlying Mechanisms ◽  
The One ◽  
Immune Defences ◽  
Recurrent Theme

To Darwin, parasites were fascinating examples of adaptation but their significance as selective factors for a wide range of phenomena has only been studied in depth over the last few decades. This work has had its roots in behavioural/evolutionary ecology on the one hand, and in population biology/ecology on the other, thus shaping a new comprehensive field of ‘evolutionary parasitology’. Taking parasites into account has been a success story and has shed new light on several old questions such as sexual selection, the evolution of sex and recombination, changes in behaviour, adaptive life histories, and so forth. In the process, the topic of ecological immunology has emerged, which analyses immune defences in a framework of costs and benefits. Throughout, a recurrent theme is how to appropriately integrate the underlying mechanisms as evolved boundary conditions into a framework of studying the adaptive value of traits. On the conceptual side, major questions remain and await further study.

Small-scale temporal and spatial variation in Atlantic cod (Gadus morhua) life history

2003 ◽  
Vol 60 (9) ◽  
pp. 1111-1121 ◽  
Author(s):  
Tara M McIntyre ◽  
Jeffrey A Hutchings
Keyword(s):  
Body Mass ◽  
Life Histories ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Spatial Scales ◽  
Gonadosomatic Index ◽  
Small Scale ◽  
Hepatosomatic Index ◽  
Georges Bank ◽  
High Fecundity

Life histories of Atlantic cod (Gadus morhua) from the Gulf of St. Lawrence south to Georges Bank differ significantly through time and space. Within the Southern Gulf, fecundity per unit body mass differed by more than 40% over short (2 years) and long (42–45 years) periods of time. Significant variation in size-specific fecundity is also evident among populations: Southern Gulf cod produce almost 30% more eggs per unit body mass than those on Georges Bank, whereas fecundity of Scotian Shelf cod is almost half that of cod in Sydney Bight. Compared with those on Georges Bank, Southern Gulf cod life histories are characterized by high fecundity, late maturity, high gonadosomatic index, and large eggs. Relative to the influence of body size, neither temporal nor spatial differences in fecundity can be attributed to physiological condition, as reflected by liver weight, hepatosomatic index, and Fulton's K. Delayed maturity and higher reproductive allotment among Southern Gulf cod can be explained as selection responses to slower growth, higher prereproductive mortality, and fewer lifetime reproductive events. Patterns of covariation in heritable, fitness-related traits suggest the existence of adaptive variation and evolutionarily significant units at spatial scales considerably smaller than the species range in the Northwest Atlantic.

Community Ecology of Stream Fishes: Concepts, Approaches, and Techniques

2010 ◽  
Keyword(s):  
Great Plains ◽  
Life Histories ◽  
Environmental Heterogeneity ◽  
Environmental Variability ◽  
Spatial Scales ◽  
Stream Fish ◽  
Metapopulation Dynamics ◽  
Stream Fishes ◽  
Spatial And Temporal Scales ◽  
Trade Offs

<em>Abstract</em>.—Stream fishes carry out their life histories across broad spatial and temporal scales, leading to spatially structured populations. Therefore, incorporating metapopulation dynamics into models of stream fish populations may improve our ability to understand mechanisms regulating them. First, we reviewed empirical research on metapopulation dynamics in the stream fish ecology literature and found 31 papers that used the metapopulation framework. The majority of papers applied no specific metapopulation model, or included space only implicitly. Although parameterization of spatially realistic models is challenging, we suggest that stream fish ecologists should incorporate space into models and recognize that metapopulation types may change across scales. Second, we considered metacommunity theory, which addresses how trade-offs among dispersal, environmental heterogeneity, and biotic interactions structure communities across spatial scales. There are no explicit tests of metacommunity theory using stream fishes to date, so we used data from our research in a Great Plains stream to test the utility of these paradigms. We found that this plains fish metacommunity was structured mainly by spatial factors related to dispersal opportunity and, to a lesser extent, by environmental heterogeneity. Currently, metacommunity models are more heuristic than predictive. Therefore, we propose that future stream fish metacommunity research should focus on developing testable hypotheses that incorporate stream fish life history attributes, and seasonal environmental variability, across spatial scales. This emerging body of research is likely to be valuable not only for basic stream fish ecological research, but also multispecies conservation and management.

Life histories, ecological tolerance limits, and the evolution of geographic range size in Eucalyptus (Myrtaceae)

2005 ◽  
Vol 53 (6) ◽  
pp. 501 ◽  
Author(s):  
Sally Mathews ◽  
Stephen P. Bonser
Keyword(s):  
Life History ◽  
Drought Tolerance ◽  
Life Histories ◽  
Spatial Scales ◽  
Geographic Range ◽  
Range Size ◽  
Tolerance Limits ◽  
Physiological Tolerance ◽  
Australian Continent ◽  
The Impact

Current theories explaining variability in species geographic range sizes in plants tend to focus on how traits associated with either physiological tolerance limits or life histories are related to range size. In trees, aspects of both physiological tolerance (e.g. drought tolerance) and life history (e.g. life span and growth rate) are related to stem traits such as wood density and height relative to diameter. We examined how the evolution of stem traits is related to geographic range sizes in Eucalyptus at two spatial scales: across the Australian continent and within the wet forests near the east coast of Australia. Geographic range sizes were estimated from herbarium records. Stem trait data were collected from both natural populations and published sources. We used phylogenetically independent contrasts to test for evolutionary associations between stem traits and geographic range sizes. Across Australia, the evolution of stem traits conferring drought tolerance were not consistently associated greater range sizes. This was surprising since arid and semi-arid environments are geographically expansive. Within the eastern forests, the evolution of stem traits defining slow growing, competitively dominant life histories were associated with greater range sizes. These stem traits should confer both a capacity to disperse into previously unoccupied habitats and the ability to persist in habitats already occupied. Traits associated with physiological tolerance and life history had significant effects on the evolution of range sizes in Eucalyptus. However, we demonstrate that the impact of these traits on range size evolution depends on both environmental conditions and the scale at which these traits are examined.

Laboulbeniomycetes: Intimate Fungal Associates of Arthropods

2021 ◽  
Vol 66 (1) ◽  
pp. 257-276 ◽  
Author(s):  
Danny Haelewaters ◽  
Meredith Blackwell ◽  
Donald H. Pfister
Keyword(s):  
Population Biology ◽  
Life Histories ◽  
Invasion Biology ◽  
Species Discovery ◽  
Phylogenetic Studies ◽  
Intimate Association ◽  
Red Algal ◽  
Molecular Phylogenetic ◽  
Parasitic Worms ◽  
Host Parasite

Arthropod–fungus interactions involving the Laboulbeniomycetes have been pondered for several hundred years. Early studies of Laboulbeniomycetes faced several uncertainties. Were they parasitic worms, red algal relatives, or fungi? If they were fungi, to which group did they belong? What was the nature of their interactions with their arthropod hosts? The historical misperceptions resulted from the extraordinary morphological features of these oddly constructed ectoparasitic fungi. More recently, molecular phylogenetic studies, in combination with a better understanding of life histories, have clearly placed these fungi among filamentous Ascomycota (subphylum Pezizomycotina). Species discovery and research on the classification of the group continue today as arthropods, and especially insects, are routinely collected and examined for the presence of Laboulbeniomycetes. Newly armed with molecular methods, mycologists are poisedto use Laboulbeniomycetes–insect associations as models for the study of a variety of basic evolutionary and ecological questions involving host–parasite relationships, modes of nutrient intake, population biology, host specificity, biological control, and invasion biology. Collaboration between mycologists and entomologists is essential to successfully advance knowledge of Laboulbeniomycetes and their intimate association with their hosts.

scholarly journals From an irrigation system to an ecological asset: adding environmental flows establishes recovery of a threatened fish species

2019 ◽  
Vol 70 (9) ◽  
pp. 1295 ◽  
Author(s):  
Ivor Stuart ◽  
Clayton Sharpe ◽  
Kathryn Stanislawski ◽  
Anna Parker ◽  
Martin Mallen-Cooper
Keyword(s):  
Water Level ◽  
Fish Species ◽  
Life Histories ◽  
Environmental Flows ◽  
Irrigation System ◽  
Spatial Scales ◽  
Environmental Water ◽  
Environmental Flow ◽  
Murray Cod ◽  
Riverine Fish

Worldwide, riverine fish are the target of environmental water because populations have declined in lotic river habitats following river regulation. Murray cod is an endangered Australian riverine fish with remaining populations associated with lotic river reaches with instream habitat, including some creeks operated as part of irrigation systems. Our objectives were to develop a life history model, apply the building block method of environmental flows to enhance the abundance of juvenile Murray cod and promote population recovery. From 2008 to 2018 we evaluated changes to Murray cod juvenile abundance before and after implementation of a perennial environmental flow regime that began in 2013. During the first year of the environmental flow, larvae were collected as evidence of spawning. Murray cod abundance can be enhanced with environmental flows that target: (1) an annual spring spawning or recruitment flow with no rapid water level drops; (2) maximising hydrodynamic complexity (i.e. flowing habitats that are longitudinally continuous and hydrodynamically complex); and (3) an annual base winter connection flow. Recognition that incorporating hydraulics (water level and velocity) at fine and coarse time scales, over spatial scales that reflect life histories, provides broader opportunities to expand the scope of environmental flows to help restore imperilled fish species in regulated ecosystems.

Additive Diversity Partitioning of Reef Fishes across Multiple Spatial Scales

2008 ◽  
Vol 44 (1) ◽  
pp. 90-101 ◽  
Author(s):  
Fabián A. Rodríguez-Zaragoza ◽  
Jesús E. Arias-González
Keyword(s):  
Spatial Scales ◽  
Reef Fishes ◽  
Diversity Partitioning ◽  
Multiple Spatial Scales
Sign in / Sign up

Export Citation Format

Share Document