Posts tagged animals

Photo 1
Notes
Posted 1 year ago
Oh, little spidey pal. We’ve all been there. Kind of. Of course, the wolf spider Schizocosa ocreata doesn’t have to undergo the torturous embarrassment of doing the ‘wrong’ dance in a misguided attempt to court a mate, or even to win a tv show which probably isn’t fronted by Simon Cowell but I couldn’t be bothered looking that up because REALLY. Further to this, these wolf spiders employ tactics to ensure that they don’t miss an opportunity to impress females they may not have seen, but which are being courted by other males in the vicinity. A new study published in this month’s issue of the journal ‘Biology Letters’ indicates that males of this species ‘eavesdrop’ on their rivals, as well as engaging in ‘signal matching’. If a wandering male notices that another male is performing a courtship dance, then he may well do the same; while he will incur costs due to the energetic nature of the display, this must be traded off with the potential fitness cost associated with missing a mating opportunity. However, this isn’t even the coolest part of this study: these male wolf spiders show behavioural plasticity, where they can actually alter their courtship behaviour depending on the behaviour of others, including changing their ‘tapping’ rates based upon that of their rivals! They may be attempting to outcompete, or synchronise with those around them. To continue the tenuous link to ‘talent’ shows etc, it’s not vastly unlike those ‘flash mobs’ that were all the rage a year or two back. Except far less shit, obviously. Check out the research here - Clark et al (2005). Eavesdropping and signal matching in visual courtship displays of spiders. Biology Letters. Original image stolen unceremoniously from Zen Faulkes’ blog, where you should read some cool stuff about females of this species being massive gluttons*. *so, yeah, the spider in the picture might be a female. I don’t really know how to check spider sex. Spiders are gross anyway. HAH. Zoom

Oh, little spidey pal. We’ve all been there. Kind of.

Of course, the wolf spider Schizocosa ocreata doesn’t have to undergo the torturous embarrassment of doing the ‘wrong’ dance in a misguided attempt to court a mate, or even to win a tv show which probably isn’t fronted by Simon Cowell but I couldn’t be bothered looking that up because REALLY. Further to this, these wolf spiders employ tactics to ensure that they don’t miss an opportunity to impress females they may not have seen, but which are being courted by other males in the vicinity.

A new study published in this month’s issue of the journal ‘Biology Letters’ indicates that males of this species ‘eavesdrop’ on their rivals, as well as engaging in ‘signal matching’. If a wandering male notices that another male is performing a courtship dance, then he may well do the same; while he will incur costs due to the energetic nature of the display, this must be traded off with the potential fitness cost associated with missing a mating opportunity.

However, this isn’t even the coolest part of this study: these male wolf spiders show behavioural plasticity, where they can actually alter their courtship behaviour depending on the behaviour of others, including changing their ‘tapping’ rates based upon that of their rivals! They may be attempting to outcompete, or synchronise with those around them. To continue the tenuous link to ‘talent’ shows etc, it’s not vastly unlike those ‘flash mobs’ that were all the rage a year or two back.

Except far less shit, obviously.

Check out the research here - Clark et al (2005). Eavesdropping and signal matching in visual courtship displays of spiders. Biology Letters.

Original image stolen unceremoniously from Zen Faulkes’ blog, where you should read some cool stuff about females of this species being massive gluttons*.

*so, yeah, the spider in the picture might be a female. I don’t really know how to check spider sex. Spiders are gross anyway. HAH.

Photo
Posted 1 year ago
A chivalrous gentleman caller should always take a gift along when visiting a lady, and this often holds true in the animal kingdom. Such items are usually nutritional - perhaps wine, chocolates, a fly snatched from a spider’s web, a gelatinous substance synthesised internally beforehand - and often advertised by the male during the courtship phase. Females may then be able to assess the quality of these ‘nuptial gifts’, and shun those males who have been so rude as to turn up empty-handed. In empidid flies, such as the dance fly Empis opaca pictured above, males usually fly in a swarm at a landmark site, holding captured prey beneath them. Females can compare the gifts available, select a male, then take the offering in order to assess it properly before deciding whether to accept him as a partner. Not only has the gift shown here secured this male a mating, but it also means that she has extra nutrition which can be used to furnish her eggs. The world of nuptial gifts and courtship feeding in invertebrates is wide-ranging, species-specific, and often quite bizarre, so we shall be coming back to them again in future. How bizarre, you ask? Well, in the particular species pictured here, males often have success with females after having carefully prepared a balloon of willow-seed fluff, which they offer up instead of a dead fly. Perhaps this shows that they are sensitive, arty souls? More likely that they are taking advantage of a sensory bias with little adaptive value, but we all get fooled sometimes… For further reading on this topic, I recommend Karim Vahed’s excellent 2007 Ethology review ‘All that glisters is not gold: sensory bias, sexual conflict and nuptial feeding in insects and spiders’. Original photograph taken from http://www.wildaboutbritain.co.uk/archive/showphoto.php/photo/94766 Zoom

A chivalrous gentleman caller should always take a gift along when visiting a lady, and this often holds true in the animal kingdom. Such items are usually nutritional - perhaps wine, chocolates, a fly snatched from a spider’s web, a gelatinous substance synthesised internally beforehand - and often advertised by the male during the courtship phase. Females may then be able to assess the quality of these ‘nuptial gifts’, and shun those males who have been so rude as to turn up empty-handed.

In empidid flies, such as the dance fly Empis opaca pictured above, males usually fly in a swarm at a landmark site, holding captured prey beneath them. Females can compare the gifts available, select a male, then take the offering in order to assess it properly before deciding whether to accept him as a partner. Not only has the gift shown here secured this male a mating, but it also means that she has extra nutrition which can be used to furnish her eggs.

The world of nuptial gifts and courtship feeding in invertebrates is wide-ranging, species-specific, and often quite bizarre, so we shall be coming back to them again in future. How bizarre, you ask? Well, in the particular species pictured here, males often have success with females after having carefully prepared a balloon of willow-seed fluff, which they offer up instead of a dead fly. Perhaps this shows that they are sensitive, arty souls? More likely that they are taking advantage of a sensory bias with little adaptive value, but we all get fooled sometimes…

For further reading on this topic, I recommend Karim Vahed’s excellent 2007 Ethology review ‘All that glisters is not gold: sensory bias, sexual conflict and nuptial feeding in insects and spiders’.

Original photograph taken from http://www.wildaboutbritain.co.uk/archive/showphoto.php/photo/94766

Photo 8
Notes
Posted 1 year ago
Sometimes, preventing your partner from going off and pumping someone else can be a bit of a drag. It might even entail hanging out with them for a post-copulatory period (often known as ‘mate harassment’, although I kind of wish my girlfriend* would stop referring to it as that). The males of a number of species - including the rather adorable buff-tailed bumble bee Bombus terrestris, above - have developed a handy little technique whereby they secrete a special fluid into a female’s genital tract at the end of copulation. This fluid hardens to form a ‘mating plug’. While females can expel them after a period of time, it just might be long enough that this first male’s sperm get a bit of a jump on the next guy to try his luck. It’s also thought that some of the chemicals in these mating plugs may make females less receptive to further matings for a little while! All of which gives our plucky hero more time to go and do what he does best (e.g., watch ‘the game’, get more matings, or sting some nosy researchers in the face). *I’m not telling her about this blog Photograph used under a creative commons licence, and courtesy of Africa Gomez at http://abugblog.blogspot.com/ Zoom

Sometimes, preventing your partner from going off and pumping someone else can be a bit of a drag. It might even entail hanging out with them for a post-copulatory period (often known as ‘mate harassment’, although I kind of wish my girlfriend* would stop referring to it as that).

The males of a number of species - including the rather adorable buff-tailed bumble bee Bombus terrestris, above - have developed a handy little technique whereby they secrete a special fluid into a female’s genital tract at the end of copulation. This fluid hardens to form a ‘mating plug’. While females can expel them after a period of time, it just might be long enough that this first male’s sperm get a bit of a jump on the next guy to try his luck. It’s also thought that some of the chemicals in these mating plugs may make females less receptive to further matings for a little while!

All of which gives our plucky hero more time to go and do what he does best (e.g., watch ‘the game’, get more matings, or sting some nosy researchers in the face).

*I’m not telling her about this blog

Photograph used under a creative commons licence, and courtesy of Africa Gomez at http://abugblog.blogspot.com/