Comment on ants etc. - Birding/Outdoor Tip for the Day

To: "'David'" <>, "'Margaret Leggoe'" <>
Subject: Comment on ants etc. - Birding/Outdoor Tip for the Day
From: "Philip Veerman" <>
Date: Sun, 14 Dec 2014 12:21:01 +1100
I know this is a diversion from the original and not about birds, but it is about the birds and the bees and of course many of you know this but some won't and may be interested. I was going to type out what is the most interesting thing about this order of insects but then thought I could save myself some time by copying the Wikipedia entry on haplodiploidy (with minor edits and additions from me). I will admit it taught me something. For 39 years I thought is was a system unique to the insect order  Hymenoptera (bees, ants, and wasps), but it appears not, although it is characteristic of them and important to their social life. It does go a long way towards explaining why these animals are so vigorous in defence of their colonies.

Haplodiploidy is a sex-determination system in which males develop from unfertilized eggs and are haploid, and females develop from fertilized eggs and are diploid.[1] Haplodiploidy is sometimes called arrhenotoky.

Haplodiploidy determines the sex in all members of the insect order Hymenoptera (bees, ants, and wasps),[2]p408 Coccidae,[3] and the Thysanoptera ('thrips').[4] The system also occurs sporadically in some spider mites, Hemiptera, Coleoptera (bark beetles), and rotifers.

In this system, sex is determined by the number of sets of chromosomes an individual receives. An offspring formed from the union of a sperm and an egg and is diploid (two) it develops as a female, and an unfertilized egg develops as a male. This means that the males have half the number of chromosomes that a female has, and are haploid.

The haplodiploid sex-determination system has these peculiarities. A male has no father and cannot have sons, but he has a grandfather and can have grandsons (obviously only by inheritance from his mother or daughter) . Additionally, if a eusocial-insect colony has only one queen, and she has only mated once (which is the common system), then the relatedness between all the workers (diploid females) in a hive or nest is 0.75. This means the workers in such monogamous single-queen colonies are significantly more closely related than in other sex determination systems where the relatedness of siblings is usually no more than 0.5. It is this point which drives the kin selection theory of how eusociality evolved.[2]:465 Whether haplodiploidy did in fact pave the way for the evolution of eusociality is still a matter of debate.[5][6] The chromosomes of workers and queens are the same, it is the feeding of the larvae by their older sisters, believed to be under instruction from their mother, that sets whether they become workers or queens.

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).[4]

Haplodiploidy is not the same thing as an XO sex-determination system. In Haplodiploidy, males receive one half of the chromosomes that female receive, including autosomes. In an XO sex-determination system, males and females receive an equal number of autosomes, but when it comes to sex chromosomes, females will receive two X chromosomes while males will receive only a single X chromosome.

Also this other reference that tells a similar story somewhat better which I am pasting below without any edits from me:


Hymenoptera, the Order of insects that includes the bees, ants and wasps, has an interesting and unusual genetic method of sex determination. Males are haploid--they have only one copy of each chromosome--while females are diploid--two copies of each chromosome. Female Hymenoptera come about in the usual way, with a sperm from a male fertilizing a female's egg. One set of chromosomes comes from the father, the other from the mother, yielding a diploid daughter.

Males, on the other hand, have a mother but no father. Males develop from an unfertilized egg, making them haploid. A female hymnopteran can have sons even if she never mates. Sex determination of this sort--haploid males and diploid females--is called haplodiploidy. Some other kinds of animals have the same sort of method of sex determination, but it is best studied in Hymenoptera.

Gender is actually determined by a single gene (at least in bees, in which this is well explored) (Beye et al. 2003). If there is only one copy of the gene, because the animal is haploid, then the animal develops as a male. If there are two copies (representing two chromosomes) and they differ in their DNA sequences, then the animal is female. In other words, an animal that is heterozygous for the sex determination gene is a female. A homozygous diploid animal develops as a sterile male. In honey bees the homozygous diploids are killed as larvae, representing considerable waste to the colony. This means that inbreeding in the Hymenoptera is costly, and most Hymenoptera avoid inbreeding.

Beyond this intriguing mechanism, haplodiploidy has important consequences that seem to affect social behavior:

  1. If a queen mates only once, her daughters are highly related to each other (called supersisters), because the father's sperm are all identical.
  2. A female is more related to her sisters (on average, 75% similar) than she is to her own daughters (on average 50% similar).
  3. A female is more related to her son (50 % similar) than she is to a brother (on average, 25% similar).

These three factors combine to create a condition in which it may be more advantageous, evolutionarily speaking, for a female to help her mother produce sisters (to the female in question) than to produce her own daughters. Thus haplodiploidy opens the way for the evolution of a worker caste, devoted to helping their mother. If workers evolve under these conditions, then we would expect:

  • That all workers will be female (males have no special pattern of relatedness in a haplodiploid system that would make working advantageous to them
  • That workers will help their mother to lay and rear females, but
  • That workers would prefer to lay their own male offspring, rather than rear brothers

In fact, Hymenoptera workers are uniformly female and conflict between the queen and the workers over who lays the males eggs in a nest is common. The role of haplodiploidy in the evolution of worker Hymenoptera fits into an overall theory of how genetic similarity affects social behavior called kin selection which was developed by W. D. Hamilton.

Beye M, Hasselmann M, Fondrk MK, Page RE, Omholt SW 2003 The gene csd is the primary signal for sexual development in the honeybee and encodes an SR-type protein. CELL 114 (4): 419-429 
Hamilton W. D. 1964 The evolution of social behavior I. J Theor Biol 7:1-16 
Hamilton W. D. 1964 The evolution of social behavior II. J Theor Biol 7:17-52.

-----Original Message-----
From: David [
Sent: Sunday, 14 December 2014 7:51 AM
To: 'Margaret Leggoe'; 'Mark Clayton'
Cc: 'Matthew Willis'; 'CanberraBirds'
Subject: RE: [canberrabirds] Birding/Outdoor Tip for the Day

All ants are related to bees and wasps at the level of “order” and the sting of all ants is in the tail as far as I can see.



From: Margaret Leggoe [
Sent: Saturday, 13 December 2014 2:24 PM
To: Mark Clayton
Cc: Matthew Willis; CanberraBirds
Subject: Re: [canberrabirds] Birding/Outdoor Tip for the Day


Bull ants, apparently, are related to wasps and have a sting in the tail. So it depends on which end of the ant attacks you, how severe the bite. The sting in the tail is the one to be feared. 

Margaret Leggoe 

<Prev in Thread] Current Thread [Next in Thread>

The University of NSW School of Computer and Engineering takes no responsibility for the contents of this archive. It is purely a compilation of material sent by many people to the Canberra Ornithologists Group mailing list. It has not been checked for accuracy nor its content verified in any way. If you wish to get material removed from the archive or have other queries about the list contact David McDonald, list manager, phone (02) 6231 8904 or email . If you can not contact David McDonald e-mail Andrew Taylor at this address: andrewt@cse.unsw.EDU.AU