Male Fertility in Natural Populations of Red Deer Is Determined by Sperm Velocity and the Proportion of Normal Spermatozoa1

Abstract If genetic variation for fitness traits in natural populations (“standing” variation) is maintained by recurrent mutation, then quantitative-genetic properties of standing variation should resemble those of newly arisen mutations. One well-known property of standing variation for fitness traits is inbreeding depression, with its converse of heterosis or hybrid vigor. We measured heterosis for three fitness traits, pre-adult viability, female fecundity, and male fertility, among a set of inbred Drosophilia melanogaster lines recently derived from the wild, and also among a set of lines that had been allowed to accumulate spontaneous mutations for over 200 generations. The inbred lines but not the mutation-accumulation (MA) lines showed heterosis for pre-adult viability. Both sets of lines showed heterosis for female fecundity, but heterosis for male fertility was weak or absent. Crosses among a subset of the MA lines showed that they were strongly differentiated for male fertility, with the differences inherited in autosomal fashion; the absence of heterosis for male fertility among the MA lines was therefore not caused by an absence of mutations affecting this trait. Crosses among the inbred lines also gave some, albeit equivocal, evidence for male fertility variation. The contrast between the results for female fecundity and those for male fertility suggests that mutations affecting different fitness traits may differ in their average dominance properties, and that such differences may be reflected in properties of standing variation. The strong differentiation among the MA lines in male fertility further suggests that mutations affecting this trait occur at a high rate.

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Chromosomal polymorphism for a heterochromatic supernumerary segment in a natural population of Tulipa australis Link (Liliaceae)

Canadian Journal of Genetics and Cytology ◽

10.1139/g85-095 ◽

1985 ◽

Vol 27 (6) ◽

pp. 633-638 ◽

Cited By ~ 7

Author(s):

C. Ruiz Rejón ◽

M. Ruiz Rejón

Keyword(s):

Sierra Nevada ◽

Male Fertility ◽

Natural Populations ◽

Chromosomal Polymorphism ◽

Supernumerary Chromosome ◽

The Other ◽

Submetacentric Chromosome ◽

Sexually Transmitted ◽

Extra Segment ◽

I Cells

Five hundred bulbs of Tulipa australis Link, and where possible the associated young flowers, have been analysed cytogenetically in four natural populations collected from the Sierra Nevada of Spain. A majority of these were diploid (2n = 24), but a few triploids (3n = 36) were present in the population from the highest altitude. All the diploid plants from three of these populations were basic homozygotes with homomorphic bivalents. In one population, however, three types of plants were identified: homozygous standard plants (80%), plants heterozygous for a large supernumerary chromosome segment (19%), and plants homozygous for its same segment (1%). The segment was located terminally on the short arm of a submetacentric chromosome. It was heteropycnotic at meiotic prophase, showed dark C-banding at metaphase I, and was visible as a prominent heterochromatic chromocentre at interphase. The segment divided reductionally in a majority of anaphase I cells (88%), which means that chiasmata tend to be excluded from the arm carrying the segment. Seeds obtained from plants homozygous for the extra segment always carried one such a segment. One-half of the seedlings of heterozygous plants are themselves heterozygotes for the extra segment, while the other half lack the segment. Finally, 11% of the seeds from bulbs without a segment turned out to be segment heterozygotes. From these results, it is deduced that the extra segment is sexually transmitted in a Mendelian fashion and that it has little or no effect on male fertility and fecundity.Key words: polymorphism, chromosomal supernumerary segment, Tulipa australis.

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Genetic diversity in European red deer (Cervus elaphus L.): anthropogenic influences on natural populations

Comptes Rendus Biologies ◽

10.1016/s1631-0691(03)00025-8 ◽

2003 ◽

Vol 326 ◽

pp. 37-42 ◽

Cited By ~ 57

Author(s):

Günther B Hartl ◽

Frank Zachos ◽

Karl Nadlinger

Keyword(s):

Genetic Diversity ◽

Cervus Elaphus ◽

Red Deer ◽

Natural Populations ◽

Anthropogenic Influences

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Sperm traits and male fertility in natural populations

Reproduction ◽

10.1530/rep-07-0143 ◽

2007 ◽

Vol 134 (1) ◽

pp. 19-29 ◽

Cited By ~ 62

Author(s):

Montserrat Gomendio ◽

Aurelio F Malo ◽

Julian Garde ◽

Eduardo R S Roldan

Keyword(s):

Swimming Speed ◽

Male Fertility ◽

Semen Quality ◽

Sperm Quality ◽

Natural Populations ◽

Economic Benefits ◽

High Fertility ◽

Domestic Livestock ◽

Antler Size ◽

Sperm Swimming Speed

Male fertility has seldom been studied in natural populations because it has been assumed that strong selection would result in uniformly high values among males, and therefore mating success has been equated with fertilisation success. In contrast, male fertility has received much attention in studies of domestic livestock, where economic benefits rely on improving productivity, and in human infertility studies, where the efficiency of treatments depends on understanding which ejaculate traits explain reproductive failures and predict success at assisted conception. Despite years of efforts, no conclusive results have been obtained, probably because such studies have focused on opposite extremes of the range with little variation: domestic livestock have often been subject to strong artificial selection for high fertility, and human patients requiring treatment have compromised fertility. Recent findings from natural populations of red deer have shown that males differ markedly in their fertility, and have revealed the degree of variation found in different semen traits, both between and within males. Fertility trials have shown that male fertility is determined mainly by sperm swimming speed and the proportion of normal sperm, when sperm numbers are kept constant. Sperm design exerts a strong influence on sperm swimming speed, with faster swimming sperm having elongated heads, shorter midpieces and a longer principal plus terminal pieces in relation to total flagellum length. Thus, the large inter-male variation in sperm design found among natural populations underlies differences in sperm swimming speed which, in turn, determine differences in male fertility rates. Secondary sexual characters are honest indicators of male fertility, so males with large and elaborated antlers have larger testes and faster swimming sperm. Testosterone does not seem to mediate the relationship between antler size and semen quality, since it is associated with sperm production, but not with sperm quality or antler size. Finally, more fertile males produce a greater proportion of sons, who will inherit the semen traits which will enhance their fertility.

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Male Fertility and Sex Ratio at Birth in Red Deer

Science ◽

10.1126/science.1133064 ◽

2006 ◽

Vol 314 (5804) ◽

pp. 1445-1447 ◽

Cited By ~ 63

Author(s):

M. Gomendio ◽

A. F. Malo ◽

A. J. Soler ◽

M. R. Fernandez-Santos ◽

M. C. Esteso ◽

...

Keyword(s):

Sex Ratio ◽

Male Fertility ◽

Red Deer ◽

Sex Ratio At Birth

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What does testosterone do for red deer males?

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2008.1367 ◽

2008 ◽

Vol 276 (1658) ◽

pp. 971-980 ◽

Cited By ~ 55

Author(s):

A.F Malo ◽

E.R.S Roldan ◽

J.J Garde ◽

A.J Soler ◽

J Vicente ◽

...

Keyword(s):

Red Deer ◽

Sperm Quality ◽

Natural Populations ◽

Reproductive Investment ◽

Parasite Load ◽

Parasite Resistance ◽

Testosterone Levels ◽

Captive Populations ◽

Testes Size ◽

Sexual Traits

Testosterone has been proposed to have a dual effect, enhancing sexual traits while depressing parasite resistance in males. Here, we test this hypothesis in red deer, examining males from captive populations during the whole annual cycle and males from natural populations during the breeding season. We first explored the effects of body size, age and sampling date on testosterone to avoid confounding effects. Our results show that in captive populations seasonal changes in testosterone levels were mirrored by changes in testes size, and that during the rut there was a strong correlation between both. In natural populations, males with higher testosterone levels had larger testes, improved sperm quality, smaller burr diameter, stronger antlers, higher haematocrit levels, and increased nematode parasite load. By contrast, no significant relationship was found between testosterone and spleen size or tick parasite load. We conclude that testosterone (i) improves males' reproductive investment and physical stamina, (ii) improves antler strength but reduces burr diameter, and (iii) imposes a cost in terms of depressed parasite resistance.

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Intramale variation in sperm size: functional significance in a polygynous mammal

PeerJ ◽

10.7717/peerj.1478 ◽

2015 ◽

Vol 3 ◽

pp. e1478 ◽

Cited By ~ 1

Author(s):

José Luis Ros-Santaella ◽

Eliana Pintus ◽

José Julián Garde

Keyword(s):

Sexual Selection ◽

Red Deer ◽

Sperm Morphology ◽

Size Variation ◽

Sperm Velocity ◽

Selective Force ◽

Animal Kingdom ◽

Normal Sperm ◽

Selection Mechanisms ◽

Sperm Size

Studies concerning the relationships between sperm size and velocity at the intraspecific level are quite limited and often yielded contradictory results across the animal kingdom. Intramale variation in sperm size may represent a meaningful factor to predict sperm velocity, due to its relationship with the level of sperm competition among related taxa. Because sperm phenotype is under post-copulatory sexual selection, we hypothesized that a reduced intramale variation in sperm size is associated with sperm competitiveness in red deer. Our results show that low variation in sperm size is strongly related to high sperm velocity and normal sperm morphology, which in turn are good predictors of male fertility in this species. Furthermore, it is well known that the red deer show high variability in testicular mass but there is limited knowledge concerning the significance of this phenomenon at intraspecific level, even though it may reveal interesting processes of sexual selection. Thereby, as a preliminary result, we found that absolute testes mass is negatively associated with intramale variation in sperm size. Our findings suggest that sperm size variation in red deer is under a strong selective force leading to increase sperm function efficiency, and reveal new insights into sexual selection mechanisms.

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Two tests of Y chromosomal variation in male fertility of Drosophila melanogaster.

Genetics ◽

10.1093/genetics/125.3.527 ◽

1990 ◽

Vol 125 (3) ◽

pp. 527-534 ◽

Cited By ~ 4

Author(s):

A G Clark

Keyword(s):

Drosophila Melanogaster ◽

Y Chromosome ◽

Male Fertility ◽

Genetic Model ◽

Natural Populations ◽

Qualitative Behavior ◽

Male Mating ◽

Physiological Importance ◽

Y Chromosomes ◽

Insight Into

Abstract Deficiency mapping with Y autosome translocations has shown that the Y chromosome of Drosophila melanogaster carries genes that are essential to male fertility. While the qualitative behavior of these lesions provides important insight into the physiological importance of the Y chromosome, quantitative variation in effects on male fertility among extant Y chromosomes in natural populations may have a significant effect on the evolution of the Y chromosome. Here a series of 36 Y chromosome replacement lines were tested in two ways designed to detect subtle variation in effects on male fertility and total male fitness. The first test involved crossing males from the 36 lines to an excess of females in an attempt to measure differences in male mating success (virility) and male fecundity. The second test challenged males bearing each of the 36 Y chromosomes to competition in populations with males bearing a standard, phenotypically marked (BsY) chromosome. These tests indicated that the Y chromosome lines did not differ significantly in either male fertility or total fitness, but that interactions with autosomes approached significance. A deterministic population genetic model was developed allowing Y autosome interaction in fertility, and it is shown that, consistent with the experimental observations, this model cannot protect Y-linked polymorphism.

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