Ontogenetic Patterns of Elemental Tracers in the Vertebrae Cartilage of Coastal and Oceanic Sharks

As predators, coastal and oceanic sharks play critical roles in shaping ecosystem structure and function, but most shark species are highly susceptible to population declines. Effective management of vulnerable shark populations requires knowledge of species-specific movement and habitat use patterns. Since sharks are often highly mobile and long-lived, tracking their habitat use patterns over large spatiotemporal scales is challenging. However, the analysis of elemental tracers in vertebral cartilage can describe a continuous record of the life history of an individual from birth to death. This study examined trace elements (Li, Mg, Mn, Zn, Sr, and Ba) along vertebral transects of five shark species with unique life histories. From most freshwater-associated to most oceanic, these species include Bull Sharks (Carcharhinus leucas), Bonnethead Sharks (Sphyrna tiburo), Blacktip Sharks (Carcharhinus limbatus), Spinner Sharks (Carcharhinus brevipinna), and Shortfin Mako Sharks (Isurus oxyrinchus). Element concentrations were compared across life stages (young-of-the-year, early juvenile, late juvenile, and adult) to infer species-specific ontogenetic patterns of habitat use and movement. Many of the observed elemental patterns could be explained by known life history traits: C. leucas exhibited clear ontogenetic changes in elemental composition matching expected changes in their use of freshwater habitats over time. S. tiburo elemental composition did not differ across ontogeny, suggesting residence in estuarine/coastal regions. The patterns of elemental composition were strikingly similar between C. brevipinna and C. limbatus, suggesting they co-occur in similar habitats across ontogeny. I. oxyrinchus elemental composition was stable over time, but some ontogenetic shifts occurred that may be due to changes in migration patterns with maturation. The results presented in this study enhance our understanding of the habitat use and movement patterns of coastal and oceanic sharks, and highlights the applicability of vertebral chemistry as a tool for characterizing shark life history traits.

Download Full-text

Habitat use patterns and edge effects across a seagrass-unvegetated ecotone depend on species-specific behaviors and sampling methods

Marine Ecology Progress Series ◽

10.3354/meps12609 ◽

2018 ◽

Vol 598 ◽

pp. 21-33 ◽

Cited By ~ 5

Author(s):

C Gross ◽

C Donoghue ◽

C Pruitt ◽

JL Ruesink

Keyword(s):

Habitat Use ◽

Edge Effects ◽

Sampling Methods ◽

Use Patterns ◽

Species Specific

Download Full-text

Coalescence times, life history traits and conservation concerns: an example from four coastal shark species from the Indo-Pacific

10.22541/au.161963333.37636342/v2 ◽

2021 ◽

Author(s):

Pierre Lesturgie ◽

Serge Planes ◽

Stefano Mona

Keyword(s):

Population Structure ◽

Life History ◽

Life History Traits ◽

New Caledonia ◽

Demographic History ◽

Conservation Strategies ◽

Shark Species ◽

Effective Population ◽

Demographic Models ◽

Mobile Species

Dispersal abilities play a crucial role in shaping the extent of population genetic structure, with more mobile species being panmictic over large geographic ranges and less mobile ones organized in meta-populations exchanging migrants to different degrees. In turn, population structure directly influences the coalescence pattern of the sampled lineages, but the consequences on the estimated variation of the effective population size (Ne) over time obtained by means of unstructured demographic models remain poorly understood. However, this knowledge is crucial for biologically interpreting the observed Ne trajectory and further devising conservation strategies in endangered species. Here we investigated the demographic history of four shark species (Carharhinus melanopterus, Carharhinus limbatus, Carharhinus amblyrhynchos, Galeocerdo cuvier) with different degrees of endangered status and life history traits related to dispersal distributed in the Indo-Pacific and sampled off New Caledonia. We compared several evolutionary scenarios representing both structured (meta-population) and unstructured models and then inferred the Ne variation through time. By performing extensive coalescent simulations, we provided a general framework relating the underlying population structure and the observed Ne dynamics. On this basis, we concluded that the recent decline observed in three out of the four considered species when assuming unstructured demographic models can be explained by the presence of population structure. Furthermore, we also demonstrated the limits of the inferences based on the sole site frequency spectrum and warn that statistics based on linkage disequilibrium will be needed to exclude recent demographic events affecting meta-populations.

Download Full-text

Coalescence times, life history traits and conservation concerns: an example from four coastal shark species from the Indo‐Pacific

Molecular Ecology Resources ◽

10.1111/1755-0998.13487 ◽

2021 ◽

Author(s):

Pierre Lesturgie ◽

Serge Planes ◽

Stefano Mona

Keyword(s):

Life History ◽

Life History Traits ◽

Shark Species ◽

Coalescence Times

Download Full-text

Body size and segmentation patterns in free-living and parasitic polychaetes

Canadian Journal of Zoology ◽

10.1139/z01-033 ◽

2001 ◽

Vol 79 (5) ◽

pp. 741-745 ◽

Cited By ~ 3

Author(s):

Robert Poulin

Keyword(s):

Life History ◽

Body Length ◽

Life History Traits ◽

The Body ◽

Free Living ◽

Body Segments ◽

The Family ◽

Body Sizes ◽

Number Of Segments ◽

Over Time

Taxa that include both free-living and parasitic lineages present opportunities to examine if and how the life-history traits of parasitic organisms have diverged from those of their free-living relatives. In a comparative analysis the body sizes and numbers of body segments of parasitic polychaetes of the family Oenonidae were compared with those of free-living polychaetes from closely related families. There was no difference in body length between oenonids and free-living polychaetes. However, the parasitic oenonids attain, on average, a much higher number of body segments than their free-living counterparts. The number of segments per unit body length is also much higher in oenonids than in related free-living polychaetes. This suggests that new segments are produced at a higher rate or for longer periods in oenonids than in free-living polychaetes, in which the proliferation of new segments slows down over time to allow for the segments to grow in size. Given that each segment can produce gametes late in the life of the worm, the proliferation of segments in oenonids may be an adaptation to their parasitic life-style.

Download Full-text

Population declines of tuna and relatives depend on their speed of life

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2015.0322 ◽

2015 ◽

Vol 282 (1811) ◽

pp. 20150322 ◽

Cited By ~ 30

Author(s):

M. J. Juan-Jordá ◽

I. Mosqueira ◽

J. Freire ◽

N. K. Dulvy

Keyword(s):

Life History ◽

Life Histories ◽

Life History Traits ◽

Population Level ◽

Maximum Size ◽

Latitudinal Gradients ◽

Fishing Mortality ◽

Population Declines ◽

Wide Range ◽

Exploitation Status

Larger-bodied species in a wide range of taxonomic groups including mammals, fishes and birds tend to decline more steeply and are at greater risk of extinction. Yet, the diversity in life histories is governed not only by body size, but also by time-related traits. A key question is whether this size-dependency of vulnerability also holds, not just locally, but globally across a wider range of environments. We test the relative importance of size- and time-related life-history traits and fishing mortality in determining population declines and current exploitation status in tunas and their relatives. We use high-quality datasets of half a century of population trajectories combined with population-level fishing mortalities and life-history traits. Time-related traits (e.g. growth rate), rather than size-related traits (e.g. maximum size), better explain the extent and rate of declines and current exploitation status across tuna assemblages, after controlling for fishing mortality. Consequently, there is strong geographical patterning in population declines, such that populations with slower life histories (found at higher cooler latitudes) have declined most and more steeply and have a higher probability of being overfished than populations with faster life histories (found at tropical latitudes). Hence, the strong, temperature-driven, latitudinal gradients in life-history traits may underlie the global patterning of population declines, fisheries collapses and local extinctions.

Download Full-text

Selection is stronger in early-versus-late stages of divergence in a Neotropical livebearing fish

Biology Letters ◽

10.1098/rsbl.2015.1022 ◽

2016 ◽

Vol 12 (3) ◽

pp. 20151022 ◽

Cited By ~ 6

Author(s):

Spencer J. Ingley ◽

Jerald B. Johnson

Keyword(s):

Life History ◽

Life History Traits ◽

Single Point ◽

Evolutionary Trajectory ◽

Trait Evolution ◽

The Difference ◽

Livebearing Fish ◽

Late Stages ◽

Over Time

How selection acts to drive trait evolution at different stages of divergence is of fundamental importance in our understanding of the origins of biodiversity. Yet, most studies have focused on a single point along an evolutionary trajectory. Here, we provide a case study evaluating the strength of divergent selection acting on life-history traits at early-versus-late stages of divergence in Brachyrhaphis fishes. We find that the difference in selection is stronger in the early-diverged population than the late-diverged population, and that trait differences acquired early are maintained over time.

Download Full-text

Shallow seamounts represent speciation islands for circumglobal yellowtail Seriola lalandi

Scientific Reports ◽

10.1038/s41598-021-82501-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Sven Kerwath ◽

Rouvay Roodt-Wilding ◽

Toufiek Samaai ◽

Henning Winker ◽

Wendy West ◽

...

Keyword(s):

Life History ◽

Genetic Structure ◽

Southern Africa ◽

Life History Traits ◽

Population Connectivity ◽

Shark Species ◽

Heterogeneous Environments ◽

Genetic Structuring ◽

Yellowtail Kingfish ◽

Seriola Lalandi

AbstractPhenotypic plasticity in life-history traits in response to heterogeneous environments has been observed in a number of fishes. Conversely, genetic structure has recently been detected in even the most wide ranging pelagic teleost fish and shark species with massive dispersal potential, putting into question previous expectations of panmixia. Shallow oceanic seamounts are known aggregation sites for pelagic species, but their role in genetic structuring of widely distributed species remains poorly understood. The yellowtail kingfish (Seriola lalandi), a commercially valuable, circumglobal, epipelagic fish species occurs in two genetically distinct Southern Hemisphere populations (South Pacific and southern Africa) with low levels of gene-flow between the regions. Two shallow oceanic seamounts exist in the ocean basins around southern Africa; Vema and Walters Shoal in the Atlantic and Indian oceans, respectively. We analysed rare samples from these remote locations and from the South African continental shelf to assess genetic structure and population connectivity in S. lalandi and investigated life-history traits by comparing diet, age, growth and maturation among the three sites. The results suggest that yellowtail from South Africa and the two seamounts are genetically and phenotypically distinct. Rather than mere feeding oases, we postulate that these seamounts represent islands of breeding populations with site-specific adaptations.

Download Full-text

Coalescent times, life history traits and conservation concerns: an example from four shark species from the Indo-Pacific

10.22541/au.161963333.37636342/v1 ◽

2021 ◽

Author(s):

Pierre Lesturgie ◽

Serge Planes ◽

Stefano Mona

Keyword(s):

Population Structure ◽

Life History ◽

Life History Traits ◽

New Caledonia ◽

Demographic History ◽

Conservation Strategies ◽

Shark Species ◽

Effective Population ◽

Demographic Models ◽

Mobile Species

Dispersal abilities play a crucial role in shaping the extent of population genetic structure, with more mobile species being panmictic over large geographic ranges and less mobile ones organized in meta-populations exchanging migrants to different degrees. In turn, population structure directly influences the coalescent pattern of the sampled lineages, but the consequences on the estimated variation of the effective population size (Ne) over time obtained by means of unstructured demographic models remain poorly understood. However, this knowledge is crucial for biologically interpreting the observed Ne trajectory and further devising conservation strategies in endangered species. Here we investigated the demographic history of four shark species (Carharhinus melanopterus, Carharhinus limbatus, Carharhinus amblyrhynchos, Galeocerdo cuvier) with different degrees of endangered status and life history traits related to dispersal distributed in the Indo-Pacific and sampled off New Caledonia. We compared several evolutionary scenarios representing both structured (meta-population) and unstructured models and then inferred the Ne variation through time. By performing extensive coalescent simulations, we provided a general framework relating the underlying population structure and the observed Ne dynamics. On this basis, we concluded that the recent decline observed in three out of the four considered species when assuming unstructured demographic models can be explained by the presence of population structure. Furthermore, we also demonstrated the limits of the inferences based on the sole site frequency spectrum and warn that statistics based on linkage disequilibrium will be needed to exclude recent demographic events affecting meta-populations.

Download Full-text