Biology Reference
In-Depth Information
120
Males
Females
90
60
30
0
0
1
2
3
0
1
2
3
Number of mates
Fig 7.3
A.J. Bateman (1948) put equal numbers of male and female fruit flies
(
Drosophila melanogaster
) in bottles and scored the number of matings and offspring
produced by each individual, using genetic markers to assign parentage. For males
reproductive success goes up with number of matings, for females it does not, beyond
the first mating.
Maximum number of offspring produced
during lifetime
Table 7.1
In
polygamous or
promiscuous
species some
males have a
much higher
potential
reproductive rate
than females
Species
Male
Female
Elephant seal
100
8
Red deer
24
14
Man
888
69
Kittiwake gull
26
28
The data for man came from the Guinness Book of Records: the male was Moulay
Ismail the Bloodthirsty, Emperor of Morocco, the woman had her children in 27
pregnancies. The data for elephant seals are from Le Boeuf and Reiter (1988), for red
deer from Clutton-Brock
et al
. (1982). In the monogamous kittiwake, where male and
female invest similarly in each offspring, the difference in maximum reproductive
output is negligible (Clutton-Brock, 1983).
consequences for sexual behaviour. Where females invest more in each offspring than
do males, male courtship and mating behaviour is to a large extent directed towards
competing for and exploiting female investment, while females are expected to choose
those males who offer the best resources or genes.
