Competition, phylogeny and community structure in Corydoras

[Silurus]

Alexandrou, MA, C Oliveira, M Maillard, RAR McGill, J Newton, S Creer & MI Taylor, 2011. Competition and phylogeny determine community structure in Müllerian co-mimics. Nature 469: 84–88.

Abstract

Until recently, the study of negative and antagonistic interactions (for example, competition and predation) has dominated our understanding of community structure, maintenance and assembly. Nevertheless, a recent theoretical model suggests that positive interactions (for example, mutualisms) may counterbalance competition, facilitating long-term coexistence even among ecologically undifferentiated species. Müllerian mimics are mutualists that share the costs of predator education and are therefore ideally suited for the investigation of positive and negative interactions in community dynamics. The sole empirical test of this model in a Müllerian mimetic community supports the prediction that positive interactions outweigh the negative effects of spatial overlap (without quantifying resource acquisition). Understanding the role of trophic niche partitioning in facilitating the evolution and stability of Müllerian mimetic communities is now of critical importance, but has yet to be formally investigated. Here we show that resource partitioning and phylogeny determine community structure and outweigh the positive effects of Müllerian mimicry in a species-rich group of neotropical catfishes. From multiple, independent reproductively isolated allopatric communities displaying convergently evolved colour patterns, 92% consist of species that do not compete for resources. Significant differences in phylogenetically conserved traits (snout morphology and body size) were consistently linked to trait-specific resource acquisition. Thus, we report the first evidence, to our knowledge, that competition for trophic resources and phylogeny are pivotal factors in the stable evolution of Müllerian mimicry rings. More generally, our work demonstrates that competition for resources is likely to have a dominant role in the structuring of communities that are simultaneously subject to the effects of both positive and negative interactions.

[kim m]

Oh, I have been waiting for this for sooooo long

[racoll]

Fantastic! Corydoras in Nature !!!

Great looking paper. Will enjoy reading this one.

[racoll]

This commentary in the same edition may be a bit easier to read for the average, unscientifically minded aquarist:

Mallet, J. & Dasmahapatra, K. 2011. Evolutionary biology: Catfish mimics. Nature 469: 41–42.

Available here.

[husky_jim]

Quote from www.sciencedaily.com :

An extensive investigation of South American Corydoras catfish, reveals that catfish communities- although containing almost identically coloured and patterned fish, could actually contain three or more different species.

Establishing for the first time that many species are mimetic; that is, they evolve to share the same colour patterns for mutual benefit- the research also established that each individual community of similar looking fish comprised species belonging to different genetic lineages, but still adopting similar colour patterns.

This discovery suggests that in many cases the number of Corydoras catfish species may be higher than previously recognised. This has consequent implications for environmentalists charged with protecting environmental diversity and safeguarding the species.

This increases the challenge of conserving these species at a time when many South American rivers are experiencing large scale development involving damn building, and destruction or contamination of habitats.

Markos Alexandrou, PhD student at Bangor University and one of the paper's authors said: "Although appearing identical in terms of colour pattern, our in-depth assessments of genetic relationships, diet, body shape and colour patterns of the fish revealed that 92% of the communities we sampled comprised species that do not compete for resources.

Dr Martin Taylor, project leader at the University's School of Biological Sciences said: "This research highlights the hidden diversity and complexity found within neotropical freshwater ecosystems. Unfortunately, these habitats are also under extreme pressure from human activities."

Claudio Oliveira of project partners, (UNESP, Botucatu, Brazil) said: "Besides the unknown biodiversity and interesting evolutionary system revealed by this study, it reinforces the urgent need to preserve and manage South American environments to avoid the loss of many species yet to be discovered and described."

Very interesting

[MatsP]

I've asked Markos for a copy of the paper... After seeing Markos at two CSG conferences, I'm really looking forward to seeing this in print!

--
Mats

[kim m]

I just got in in my inbox...ohhh...the last few hours at work are going to feel looong!

[t-hak]

I'd like to have a copy if possible (address in the e-mail icon), thanks.

[Suckermouth]

Fascinating! I'll have to see if I can download this once I get back to school.

[lfinley58]

Hi all.

For those interested in this topic that may have received a copy of the paper: While the paper itself is not available for free on the Nature website there is a supplemental 27 page PDF of Charts and Tables that is available gratis. There is a large amount of information contained therein and this should be downloaded to go along with the original paper. The supplemental material can be found at the following url: http://www.nature.com/nature/journal/v4 ... 09660.html

Lee

[racoll]

There is a large amount of information contained therein and this should be downloaded to go along with the original paper.

Yes, lots of info, but shame that the journal have presented the trees as rasta rather than vector graphics. Makes searching for specific taxa hard.

[Jools]

That would be raster graphics, but yeah, I thought that too, it also makes them invisible to search engines but really a minor point in a staggeringly big piece of work. Nice to see that a small contribution to it was made by aquarists.

Jools

[racoll]

That would be raster graphics,

yes, good typo! No ganja in sight!

but really a minor point in a staggeringly big piece of work

Indeed. Even more staggering is that it is in Nature. For people that don't know, Nature is pretty much the best journal one can publish in, not just for biology, but the whole of science. Only the most groundbreaking, exceptional, and interesting research gets here. People spend their entire careers trying to publish in Nature, and from what I can gather, this is from his PhD thesis!

[Jools]

Having had my first read of the synopsis of the letter in Nature, it's really helped placed an understanding of what this means "in the river" on top of the mass of collected numerical data. Top stuff.

Jools

[sameet]

Very interesting papers on the phenomenon known as “Müllerian Mimicry”. Both complete papers available:

1) Competition and phylogeny determine community structure in Müllerian co-mimics by Alexandrou et al., 33 pages. (6 pages plus 27 suppl. pages of tables etc – as stated by lfinley58 in his post of 7th Jan 2011).

2) Catfish mimics, (2 pages) by Malet & Dasmahapatra










.

[Jools]

Sameet,

I note your post above, please avoid posting duplicate information in this section. The two noted works had already been introduced in the topic. The purpose of this forum, and to repeat what I've just recently said here, is to succinctly note and discuss works.

We are also fully cognisant of any copyright of documents and do not promote any action that breaks that law.

I also note you've sent 9 PMs looking for PDF papers to other forum members, while that's OK, you might want to write more in the style of request rather than demand and indeed note why a paper is of specific interest to you. We're happy to help, but there are limits and rules. I hope you don't mind me pointing that out.

Jools