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11.
Gender identification of shovelnose sturgeon using ultrasonic and endoscopic imagery and the application of the method to the pallid sturgeon 总被引:7,自引:0,他引:7
M. L. Wildhaber† D. M. Papoulias† A. J. DeLonay† D. E. Tillitt† J. L. Bryan† M. L. Annis† J. A. Allert† 《Journal of fish biology》2005,67(1):114-132
Monthly sampling of shovelnose sturgeon Scaphirhynchus platorynchus , a biological surrogate for the endangered pallid sturgeon Scaphirhynchus albus , was conducted to develop a multi‐seasonal profile of reproductive stages. Data collected included histological characteristics of gonads from wild caught fish and laboratory and field ultrasonic and endoscopic images. These data were used to compare effectiveness of ultrasonic and endoscopic techniques at identifying gender of adult shovelnose sturgeon at different reproductive stages. The least invasive method ( i.e . ultrasound) was least effective while the most invasive ( i.e . endoscope through an abdominal incision) was the most effective at identifying shovelnose sturgeon gender. In most cases, success rate for identifying males was greater than females, with success at identifying both genders greater in more advanced reproductive stages. Concomitantly, for most months average reproductive stage was more advanced for males than females. April and May were the months with the most advanced reproductive stage, and were the months when ultrasound was most effective. Methods were also applied in the Upper Missouri River to validate their use on pallid sturgeon Scaphirhynchus albus . Ultrasound was successful at identifying pallid sturgeon gender, however, endoscopic examination through the urogenital duct was only successful at identifying pallid sturgeon gender when the urogenital duct was not opaque. 相似文献
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B. F. J. Manly 《Biometrical journal. Biometrische Zeitschrift》1981,23(3):267-281
The situation is considered where the multivariate distribution of certain variables X1, X2, …, Xp is changing with time in a population because natural selection related to the X's is taking place. It is assumed that random samples taken from the population at times t1, t2, …, ts are available and it is desirable to estimate the fitness function wt(x1, x2,…,xp) which shows how the number of individuals with Xi = xi, i = 1, 2, …, p at time t is related to the number of individuals with the same X values at time zero. Tests for population changes are discussed and indices of the selection on the population dispersion and the population mean are proposed. The situation with a multivariate normal distribution is considered as a special case. A maximum likelihood method that can be applied with any form of population distribution is proposed for estimating wt. The methods discussed in the paper are illustrated with data on four dimensions of male Egyptian skulls covering a time span from about 4500 B.C. to about 300 A.D. In this case there seems to have been very little selection on the population dispersion but considerable selection on means. 相似文献
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《Plant Ecology & Diversity》2013,6(3-4):495-501
Background: The adaptation, evolution and function of flower colour diversity in response to changing environments are one of the oldest puzzles in plant ecology. It is logical that comparative studies on fitness of flower colour would be the most meaningful if they were conducted on the same genotype. Aims: We used Gentiana leucomelaena, which produces both white and blue flowers on different tillers of the same individual, as a model species to test adaption and fitness differences of contrasting flowers in contrasting environments. Methods: We examined seed production by white and blue flowers in response to increased temperatures (28 °C/2 °C vs. 12 °C/2 °C; 12 h light/12 h dark) in a climate chamber study and to watering in the field (+1.5 l m?2 d?1 vs. control with no supplementary irrigation). Results: For white and blue flowers warming decreased but watering increased seed number. Increased temperature and watering increased the size of seeds from white flowers, but neither warming nor watering significantly changed seed size of blue flowers. Seed size was significantly negatively correlated with seed number in the temperature treatments but positively correlated in watering treatments. The positive correlation was strong in white flowers, but the negative correlation was stronger in blue than in white flowers. Conclusions: Water availability and low temperature confer an advantage to white flowers, while warming and dry habitats favour blue flowers. These divergent responses may influence total plant fitness and thus help explain the adaptive value and evolution of flower colour diversity. 相似文献
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A. A. Kepel' 《Russian Journal of Marine Biology》2000,26(6):450-452
The alga Analipus japonicus (Harv.) Wynne displays a distinct seasonal pattern in its development in Peter the Great Bay (Sea of Japan). In winter and spring, it occurs only in the form of basal crusts, and vertical axes develop in the summer–autumn period. It reproduces mostly asexually from July to November. Algae with unilocular sporangia occur very seldom, only in June and July. 相似文献
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The flowering of Clutia pulchella was studied in a coastal scarp forest community in southern KwaZulu-Natal, South Africa. Sex dependent differences in the
frequency and magnitude of floral output were recorded, with male individuals producing 4.32 times more flowers per leaf axis
than females. Increased node production, as a manifestation of significantly increased branching, allowed for prolific flower
production in males. Energy investment per flower was marginally greater in females (0.045 J/mg), despite copious pollen production
and glandular secretion in males (0.035 J/mg). Differential flower production, reproductive organ dry mass and an unbalanced
branching ratio revealed that “per plant” expenditure towards flowering was more pronounced in males (♀ flowering × 5.04).
The elevated cost of fruit production (♀ flowering × 5.5), inclusive of imperfect fruit set, resulted in overall reproductive
expense being slightly higher for females. Such sex-dependent reproductive investment was shown to have minimal influence
on the population sex ratio, with sex frequencies and nearest neighbor distances yielding a non-significant male bias of 1.16.
No evidence of spatial asymmetry was found.
Received December 1, 1999 Accepted September 27, 2000 相似文献
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Kristjan Zobel 《Evolutionary ecology》2008,22(3):487-492
Although sexuality is considered evolutionarily progressive, clonality is very common in plants and the prevailing means of
reproduction in several community types. I discuss what could be the forces that have influenced the selection among sexual
versus non-sexual reproduction at community level. I propose that, among others, the probability of self-competition must
have been one of the key factors. The probability of meeting one’s own genes for wasteful competition is higher in communities
where clonality prevails (and relatively high mean intra-species relatedness is expected), and higher in communities with
low species diversity. On the other hand, lower diversity indicates a higher average fitness of species since the (finite)
total pool of resources is distributed among fewer population with high density. I show, using four community types with contrasting
diversity and clonality that community fitness (average fitness in the assemblage of species) can be expressed as the product
of two variables––anti-diversity and degree of sexuality. 相似文献
20.
Ting Zhang Bai‐Ge Miao Bo Wang Yan‐Qiong Peng Clive T. Darwell 《Ecological Entomology》2019,44(6):844-848
1. Species interactions in tightly bound ecological mutualisms often feature highly specialised species' roles in which competitive exclusion may preclude multi‐species coexistence. Among the 800 fig (Ficus) species, it was originally considered that each was pollinated by their own wasp (Agaonidae). However, recent investigations show that this ‘one‐to‐one’ rule often breaks down, as fig species regularly host multiple agaonids but in ways suggesting that competitive processes still mediate biodiversity outcomes. 2. A phenological survey was conducted of the fig–fig wasp pair, Ficus microcarpa and its associated pollinating wasp, alongside its sister species, the cheating wasp, in Xishuangbanna, China. 3. Reproductive output underwent extreme seasonal variation. Seed and pollinator production fell markedly during cooler, drier months, although high levels of fig production continued. However, this resource was predominantly utilised by the cheater species, which offers no pollination services. Pollinators and cheaters rarely co‐occur, suggesting that temporal coexistence is constrained by competition for access to figs. 4. The overall findings indicate periodic rearrangements of mutualism dynamics, probably resulting from a strongly seasonal environment. Sympatric co‐occurrence may result from a window of opportunity for a functionally divergent agaonid, potentially due to constraints on the main pollinator in adapting to variable year‐round conditions that prevent competitive exclusion. 相似文献