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Tarantulas'
personality determines whether they copulate with males or cannibalize them
Tarantulas'
personality determines whether they copulate with males or cannibalize them
Date:
April 22,
2014
Source:
Plataforma SINC
Summary:
Sexual cannibalism in spiders – the attack and
consumption of males by females before or after copulation – is very
widespread. A new investigation analyses the reason behind such extreme
behavior, at times even before the females have ensured the sperm’s
fertilization of their eggs.
.........................
Sexual cannibalism in spiders -- the attack and consumption
of males by females before or after copulation -- is very widespread. A new
investigation analyses the reason behind such extreme behaviour, at times even
before the females have ensured the sperm's fertilisation of their eggs.
After
copulating with a male, female spiders tend to practice sexual cannibalism,
that is to say, they attack the males and eat them. Researchers from the
Experimental Station of Arid Zones (EEZA-CSIC) have studied why, at times, this
behaviour arises before copulation, often without having ensured the sperm's
fertilisation of their eggs.
"This
tendency towards cannibalism could depend on the aggressive genetics of the
females which make them attack males in the same way as they attack prey,"
Rubén Rabaneda-Bueno, first author of the study on tarantulas published in Ethology,
explained.
In order to
evaluate the female personality for sexual cannibalism, the authors offered
randomly selected males to a group of female virgin tarantulas and documented
whether they attacked the males or copulated with them.
In addition,
prior to these meetings, they studied the voracious personality of the females
when feeding on beetles and other natural prey, among which there were more
ravenous or more docile females that differed in their fattening rate.
Finally they
searched for a connection between the cannibal personality and the nourishing
personality of the females, and whether it was related to the females being
more demanding at the time of choosing a mate.
"More
cannibalistic females were also more voracious towards their prey, and thus the
better nourished. This is surprising since they have more nutritive resources
to invest in their offspring before finding the first males," Rabaneda
added. "Their priority should be ensuring the sperm's fertilisation of
their eggs instead of eliminating their potential donors."
Cannibalism
in choosing a mate
Furthermore,
the males of this species assume an important contribution of nutrients for
which reason it would be expected that the more docile and worse nourished
females would exploit this source of food before copulation, cannibalizing the
males.
"We
reached the conclusion that there are aggressive genetics which vary among
females and make them act aggressively both when they feed off prey and when
they approach a male in courting," added Jordi Moya Laraño, director of
the study. "Others are docile in both contexts, highlighting the existence
of different personalities."
Thus, there
are females with aggressive personality that are voracious, fatten up a lot and
tend to cannibalize males when they are still virgins. On the other hand, there
are docile females that eat less prey and prefer to copulate first before
attacking their possible mates.
"While
docile females attack inferior males and prefer to mate with superior males,
aggressive females kill males regardless of their condition, which demonstrates
their inability to distinguish males as sources of sperm or food,
indiscriminately cannibalizing them," Rabaneda pointed out.
This study
affirms that different levels of aggressiveness or feminine personalities
contribute in generating variability in masculine reproductive success.
"As such, sexual cannibalism could function as a way of choosing a mate
which would also occur in various ways according to the female's
personality," he concluded.
Further
information
Cannibalism
does not depend on the size of the tarantulas.
The size of
the female was not decisive in the cannibal tendency of tarantulas, as has been
seen in other spider species. "This could seem contradictory given that we
would expect more voracious females to be bigger, noting an association not
only between voraciousness and cannibalism, but also with size," the
researcher insisted.
However, the
females store their resources in the abdomen -- the soft part of the spider,
directly linked to an increase in weight -- when they feed, beyond body size
which represents the upper rigid part and which could remain unchanged in
adulthood despite variations in weight.
Story
Source:
The above
story is based on materials provided by Plataforma SINC. Note: Materials may be edited
for content and length.
Journal
Reference:
- Rubén Rabaneda-Bueno, Sara Aguado, Carmen Fernández-Montraveta, Jordi Moya-Laraño. Does Female Personality Determine Mate Choice Through Sexual Cannibalism? Ethology, 2014; 120 (3): 238 DOI: 10.1111/eth.12197
Cite This
Page:
Plataforma SINC. "Tarantulas'
personality determines whether they copulate with males or cannibalize
them." ScienceDaily. ScienceDaily, 22 April 2014.
<www.sciencedaily.com/releases/2014/04/140422084730.htm>.
