Haplodiploidy
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Haplodiploidy is a
Haplodiploidy determines the sex in all members of the insect orders
In this system, sex is determined by the number of sets of
The haplodiploid sex-determination system has a number of peculiarities. For example, a male has no father and cannot have sons, but he has a grandfather and can have grandsons. Additionally, if a
Another feature of the haplodiploidy system is that recessive lethal and deleterious alleles will be removed from the population rapidly because they will automatically be expressed in the males (dominant lethal and deleterious alleles are removed from the population every time they arise, as they kill any individual they arise in).[3]
Haplodiploidy is not the same thing as an
Mechanisms
Several models have been proposed for the genetic mechanisms of haplodiploid sex-determination. The model most commonly referred to is the complementary allele model. According to this model, if an individual is
After mating, each fertile hymenopteran female stores sperm in an internal sac called the spermatheca. The mated female controls the release of stored sperm from within the organ: If she releases sperm as an egg passes down her oviduct, the egg is fertilized.[7] Social bees, wasps, and ants can modify sex ratios within colonies which maximizes relatedness among members and generates a workforce appropriate to surrounding conditions.[8] In other solitary hymenopterans, the females lay unfertilized male eggs on poorer food sources while laying the fertilized female eggs on better food sources, possibly because the fitness of females will be more adversely affected by shortages in their early life.[9][10] Sex ratio manipulation is also practiced by haplodiploid ambrosia beetles, who lay more male eggs when the chances for males to disperse and mate with females in different sites are greater.[11]
Sex determination in honey bees
In
There are rare instances of diploid drone larvae. This phenomenon usually arises when there is more than two generations of brother-sister mating.[13] Sex determination in honey bees is initially due to a single locus, called the complementary sex determiner (csd) gene. In developing bees, if the conditions are that the individual is heterozygous for the csd gene, they will develop into females. If the conditions are so that the individual is hemizygous or homozygous for the csd gene, they will develop into males. The instances where the individual is homozygous at this gene are the instances of diploid males.[14] Diploid males do not survive to adulthood, as the nurse worker bees will cannibalize the diploid males upon hatching.[15]
While workers can lay unfertilized eggs that become their sons, haplodiploid sex-determination system increases the individual's fitness due to indirect selection. Since the worker is more related to the queen's daughters (her sisters) than to her own offspring, helping the queen's offspring to survive helps the spread of the same genes that the worker possesses more efficiently than direct reproduction.[16]
Batches of worker bees are short lived and are constantly being replaced by the next batch, so this
Sex determination in chalcidoid wasps
In wasps of the genus Nasonia, a non-CSD method of sex determination has been documented. The most recent accepted model for this non-CSD system is called Maternal Effect Genomic Imprinting Sex Determination (MEGISD). This model involves a masculinizing/virilizing maternal effect gene that “imprints upon” the cytoplasmic component of oocytes, and an “unimprinted” paternal contribution (in female offspring) that provides a counter effect to virilization and allows for female development to occur. Since all diploid eggs become female (due to the factor originating in the male genetic contribution that prevents masculinization), this differs from CSD in that under CSD, diploid eggs can become males if they are homozygous or hemizygous.[19]
Relatedness ratios in haplodiploidy
In normal
Relatedness coefficients in haplodiploid organisms are as follows, assuming that a female has only mated once. These ratios apply, for example, throughout a bee hive, unless some
Shared gene proportions in haplo-diploid sex-determination system relationships Sex Female Male Daughter 1⁄2 1 Son 1⁄2 — Mother 1⁄2 1 Father 1⁄2 — Sister 3⁄4 1⁄2 Brother 1⁄4 1⁄2 Maternal Aunt 3⁄8 3⁄4 Maternal Uncle 1⁄8 1⁄4 Paternal Aunt 1⁄4 — Paternal Uncle 1⁄4 — Niece (sister's daughter) 3⁄8 1⁄4 Niece (brother's daughter) 1⁄4 1⁄2 Nephew (sister's son) 3⁄8 1⁄4
Under this assumption that mothers only mate once, sisters are more strongly related to each other than to their own daughters. This fact has been used to explain the evolution of eusociality in many hymenopterans. However, colonies which have workers from multiple queens or queens which have mated multiple times will have worker-to-worker relatedness which is less than worker-to-daughter relatedness, such as in Melipona scutellaris.
See also
- Green-beard effect
- Ploidy
- Pseudo-arrhenotoky
- Sexual differentiation
- Worker policing
- X chromosome
- Y chromosome
References
- ISBN 978-0-19-530761-0.
- ISBN 978-0-521-82149-0.
- ^ ISSN 0373-4137.
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- ^ van Wilgenburg, Ellen; Driessen, Gerard & Beukeboom, Leo W. Single locus complementary sex determination in Hymenoptera: an "unintelligent" design? Frontiers in Zoology 2006, 3:1
- ^ Mahowald, Michael; von Wettberg, Eric Sex determination in the Hymenoptera Swarthmore College (1999)
- S2CID 53192398.
- .
- PMID 15009259.
- ^ Sinervo, Barry Kin Selection and Haplodiploidy in Social Hymenoptera Archived 2011-07-16 at the Wayback Machine 1997
- ^ Woyka, J.; Pszczelnictwa, Zaklad; Drone Larvae from Fertilized Eggs of the Honey Bee Archived 2014-10-22 at the Wayback Machine Journal of Apiculture Research, (1963), pages 19-24
- ^ Weinstock, George M.; Robinson, Gene E., & the Honeybee Genome Sequencing Consortium Insights into social insects from the genome of the honeybee Apis mellifera Nature, volume "'443'" (2006), pages 931-949
- ^ Santomauro, Giulia; Oldham, Neil J.; Boland, Wilhelm; Engels Wolf; Cannibalism of Diploid Drone Larvae in the Honey Bee (Apis mellifera) is Released by Odd Pattern of Circular Substance Journal of Apiculture Research, volume "'43'" (2004), pages 69-74
- S2CID 46052954.
- PMID 11580023.
- ^ Davies, Nicholas B., John R. Krebs and Stuart A. West. (2012). An Introduction to Behavioral Ecology. Wiley-Blackwell. pp. 371–375.
{{cite book}}
: CS1 maint: multiple names: authors list (link) - ^ Zou, Yuan et al. “A chimeric gene paternally instructs female sex determination in the haplodiploid wasp Nasonia.” Science 370 (2020): 1115 - 1118.
- ^ ISBN 978-0-7167-4530-3.
- PMID 16701471.
Bibliography
- Beye, Martin; et al. (1999). "Unusually high recombination rate detected in the sex locus region of the honey bee (Apis mellifera)". PMID 10581277.
- Wu, Z.; et al. (2005). "Single-locus complementary sex determination absent in Heterospilus prosopidis (Hymenoptera: Braconidae)". Heredity. 95 (3): 228–234. PMID 16077738.
- Ratnieks, Francis (1988). "Reproductive harmony via mutual policing by workers in eusocial hymenoptera". American Naturalist. 132 (2): 217–236. S2CID 84742198.