Ontogenetic development of the endangered Atlantic whitefish (Coregonus huntsmani Scott, 1987) eggs, embryos, larvae, and juveniles

2007 ◽  
Vol 85 (11) ◽  
pp. 1157-1168 ◽  
Author(s):  
D.J. Hasselman ◽  
J. Whitelaw ◽  
R.G. Bradford

Atlantic whitefish ( Coregonus huntsmani Scott, 1987 ) are an endangered species endemic to Canada and are known only from Nova Scotia. Information concerning their early life-history stages — not previously described — is required to support several recovery actions under the federal Species at Risk Act (SARA). We describe the ontogenetic development of Atlantic whitefish eggs, larvae, and juveniles acquired through captive-mating of wild-caught adults, following criteria established for fishes in general and for other North American coregonine species where possible. We then conduct interspecific comparisons between Atlantic whitefish and the two most closely phylogenetically related species (i.e., lake whitefish ( Coregonus clupeaformis (Mitchill, 1818)) and cisco ( Coregonus artedii Lesueur, 1818)) to (i) identify ontogenetic differences that may facilitate field identification, (ii) determine whether differences at common ontogenetic milestones reinforce the recognition of Atlantic whitefish at the species level, and (iii) comment on whether these differences are consistent with the putative ancestral status of Atlantic whitefish. Interspecific differences were observed at all ontogenetic stages, several of which may serve as field identification criteria. Evidence for heterochrony during embryogenesis, as well as interspecific differences in egg size, myomere counts, and pigmentation patterns, substantiate the recognition of Atlantic whitefish as a valid species and support its putative ancestral status.

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 768
Author(s):  
Jerónimo Vázquez-Ramírez ◽  
Susanna E. Venn

The early life-history stages of plants, such as germination and seedling establishment, depend on favorable environmental conditions. Changes in the environment at high altitude and high latitude regions, as a consequence of climate change, will significantly affect these life stages and may have profound effects on species recruitment and survival. Here, we synthesize the current knowledge of climate change effects on treeline, tundra, and alpine plants’ early life-history stages. We systematically searched the available literature on this subject up until February 2020 and recovered 835 potential articles that matched our search terms. From these, we found 39 studies that matched our selection criteria. We characterized the studies within our review and performed a qualitative and quantitative analysis of the extracted meta-data regarding the climatic effects likely to change in these regions, including projected warming, early snowmelt, changes in precipitation, nutrient availability and their effects on seed maturation, seed dormancy, germination, seedling emergence and seedling establishment. Although the studies showed high variability in their methods and studied species, the qualitative and quantitative analysis of the extracted data allowed us to detect existing patterns and knowledge gaps. For example, warming temperatures seemed to favor all studied life stages except seedling establishment, a decrease in precipitation had a strong negative effect on seed stages and, surprisingly, early snowmelt had a neutral effect on seed dormancy and germination but a positive effect on seedling establishment. For some of the studied life stages, data within the literature were too limited to identify a precise effect. There is still a need for investigations that increase our understanding of the climate change impacts on high altitude and high latitude plants’ reproductive processes, as this is crucial for plant conservation and evidence-based management of these environments. Finally, we make recommendations for further research based on the identified knowledge gaps.


2000 ◽  
Vol 78 (11) ◽  
pp. 1420-1429 ◽  
Author(s):  
Theresa M Culley

Few studies of inbreeding depression have focused on species producing both showy, chasmogamous (CH) flowers and self-pollinated, cleistogamous (CL) flowers. The goals of this investigation were to measure the level of inbreeding depression in the North American violet, Viola canadensis L., and to determine if any fitness differences were linked to floral type (CH versus CL) rather than to cross type (self versus outcross). Hand pollinations were carried out to produce self- and outcross-pollinated CH progeny, and CL seeds were also collected. In a greenhouse, selfed and outcrossed CH flowers produced similar numbers of seeds, and both types of progeny had similar survival rates and comparable numbers of CH flowers, although outcrossed CH progeny had 14% greater vegetative biomass than selfed CH progeny. The level of inbreeding depression in V. canadensis was low, indicating that there may be few drawbacks to selfing in this species. A comparison of CL and self-pollinated CH progeny showed that, although there were differences in CH flower number, overall fitness differences were minimal. The similar performance of selfed (CL and CH) and outcrossed progeny in early life-history stages of V. canadensis suggests a history of inbreeding in the population.Key words: cleistogamy, inbreeding depression, outcrossing, selfing, Viola canadensis.


1991 ◽  
Vol 48 (10) ◽  
pp. 1820-1828 ◽  
Author(s):  
Pierre Pepin ◽  
Ransom A. Myers

Recruitment variability is commonly associated with fluctuations in abundance of marine fish populations. Previous studies have focussed on stock-specific correlative or mechanistic models or on comparisons of recruitment variations of several stocks or species. The purpose of this study is to determine whether recruitment variability of commercial marine fish populations is associated with either size or the duration of early life history stages. The analysis was performed with data from 86 stocks representing 21 species of commercial marine fish. Univariate analysis shows that neither egg size nor the length at hatch is significantly correlated with recruitment variability. The change in length during the larval phase, which is representative of the duration of the stage, is significantly positively correlated with recruitment variability. Multivariate analysis shows that recruitment variability increases with increasing length at metamorphosis but that recruitment variability is poorly associated with length at hatch. The degree of serial correlation is related to the relative duration of egg and larval stages. The results clearly indicate that recruitment variability is linked to characteristics of early life history stages.


1990 ◽  
Vol 47 (2) ◽  
pp. 335-345 ◽  
Author(s):  
Yvan Lambert ◽  
Julian J. Dodson

We tested the hypothesis that differences in the cost of freshwater migration are responsible for the different reproductive patterns exhibited by the Eastmain River (James Bay) populations of anadromous cisco and lake whitefish, as predicted by species-specific migration costs that result in interspecific differences in energy allocation to growth, survival, and reproduction. In the Eastmain River, cisco spawn at a younger age and a smaller size, have a shorter life span and show a higher fecundity and a higher mortality than lake whitefish. Assuming that the two populations are stable (being only lightly exploited), the two species spawn at an age that maximizes their lifetime fecundity. Either juvenile (between three and age at maturity) and/or adult mortality is of major importance in moulding the observed age at maturity but adult mortality may play a predominant role. Adult mortality is associated with migration, an obligatory cost representing a major proportion of the energy loss experienced by reproductive individuals. The difference in the energy cost of migration between the two species suggests that migration may play a predominant role in producing the different reproductive patterns of cisco and lake whitefish in the Eastmain River and that within the physiological and size constraints of each species, these patterns represent optimal adaptations maximizing fitness.


2021 ◽  
Vol 325 (4) ◽  
pp. 457-468
Author(s):  
L.A. Jawad ◽  
F. Mutlak ◽  
A.R.M. Mohamed ◽  
J.M. Al-Mamry ◽  
E.K. Hameed ◽  
...  

The finding of larval and juvenile specimens from the Omani coast of the Arabian Sea and the Arabian Gulf waters of Saudi Arabia and Iraq is reported for the first time. Based on available information, one larva was a leptocephalus, Conger sp. (family Congridae) and one larva of an acronurus stage belonging to the genus Acanthurus (family Acanthuridae). Also juveniles of the following families are included in the present study: Clupeidae – Tenualosa ilisha (Hamilton, 1822) and Nematalosa sp.; Dactylopteridae – Dactyloptena orientalis (Cuvier, 1829); Gobiidae – Acentrogobius sp.; Bothidae – Arnoglossus aspilos (Bleeker, 1851); Scatophagidae – Scatophagus argus (Linnaeus, 1766); Sparidae – Acanthopagrus arabicus Iwatsuki, 2013 and Sparidentex hasta (Valenciennes, 1830); Tetraodontidae – Lagocephalus sp. The discovery of the barred rather than spotted juveniles of S. argus collected from pure freshwater environment of the Shatt al-Arab River, Basrah, Iraq was remarkable; it raises questions whether there is more than one species within the nominal S. argus. For both larvae and juveniles of bothid flounders, the olfactory organ is a useful character for the examination of the developmental stage of the metamorphosing specimens. The occurrence of the different early life history stages of fishes from the three Arabian countries shows the needs them to be studied further so that inferences about the areas and periods of spawning and development of these fishes can be made more accurately.


2003 ◽  
Vol 111 (13) ◽  
pp. 1601-1607 ◽  
Author(s):  
Ruth H Milston ◽  
Martin S Fitzpatrick ◽  
Anthony T Vella ◽  
Shaun Clements ◽  
Deke Gundersen ◽  
...  

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