Interesting articles about Anemone fish and their host anemones

[mcfa2403]

Thanks for cleaning that up, I would love to participate more but at the current time I am preoccupied trying to better understand the coloring process and differences in bubble tip anemones. At the moment the deeper I dig the more confusion I find.

 

[ThRoewer]

Let's add this here too:

Social Control of Sex: Field Experiments with the Anemonefish Amphiprion bicinctus

Abstract

From the underwater station Neritica, situated in 11 m depth off the shore of the Heinz-Steinitz-Marine-Laboratory in Eilat, Israel, experiments were carried out to investigate the influence of food restriction, social status, body size and relative frequency of aggressive interactions on protandric sex change in the anemonefish A. bicinctus. Some 47 fish were tagged and observed in different conditions. Caged conditions retard, sometimes even prevent sex change in dominant males; it is suggested that this is consequent upon the ensuing food restriction, also that this mechanism operates to prevent sex change in subdominants in freeliving conditions, through the aggressive restraint of dominant males. No solitary males, caged or free, complete a sex change. Complete functional sex change occurs only in well-fed aggressively dominant males at least 100 mm in body length in the presence of a social partner. The study shows that social stimuli are vital for the initiation of sex change in these males.

This basically makes it highly unlikely that a lonely clownfish male becomes a female on his own.
It is even more unlikely for single immature juveniles to transition straight to female.

 

[mcfa2403]

A couple anemone reads I posted in a separate thread if you feel they are relevant to the topic if you would clean them up for me (haven't figured out exactly what you are doing to them yet), however they do deviate slightly from what I have seen posted thus far.
https://kuscholarworks.ku.edu/bitst...tin and Smith.1997.pdf?sequence=1&isAllowed=y

http://link.springer.com/article/10.1007/s00227-009-1201-6

 

[ThRoewer]

A couple anemone reads I posted in a separate thread if you feel they are relevant to the topic if you would clean them up for me (haven't figured out exactly what you are doing to them yet), however they do deviate slightly from what I have seen posted thus far.
https://kuscholarworks.ku.edu/bitst...tin and Smith.1997.pdf?sequence=1&isAllowed=y

http://link.springer.com/article/10.1007/s00227-009-1201-6

Interesting articles. They fit right in.

Clonality as a Taxonomic Character of Actinian Species Full PDF

Abstract

Sea anemones of some species have been considered to exist both clonally and as solitary individuals. In two temperate taxa, these alternative forms have been demonstrated through molecular techniques actually to belong to separate species. We have sequenced a variable portion of the cytochrome oxidase I mitochondrial gene from both solitary and clonal individuals of two nominal species of actinians that host anemonefish and that are abundant in Indo-Pacific reefs -- *Entacmaea quadricolor* and *Heteractis magnifica*. Our molecular data support the conclusion based on morphology that *H. magnifica* constitutes a single species from the Red Sea to French Polynesia, and encompasses both solitary and clonal morphs. The sequences from *E. quadricolor* differ from those of *H. magnifica*, but are too preliminary for assessment of whether more than a single species is represented.

Gametogenic and reproductive cycles of the sea anemone, Entacmaea quadricolor

Abstract

Host sea anemones are ecologically important as they provide habitat for obligate symbiotic anemonefish in many areas of the Indo-Pacific. Despite their importance, no information is available on their gametogenic cycles. This study aimed to address this lack of knowledge by determining the gametogenic cycles of Entacmaea quadricolor. Gonad samples were taken from January 2003 to February 2005 at North Solitary Island, Solitary Islands Marine Park, Australia using a specially developed non-lethal field biopsy sampling technique. Sampling was done 17 times during the study period, with 15"“20 individuals being sampled on each occasion. Samples were examined prior to fixation, and then histologically sectioned to determine the reproductive activity of each individual. Female anemones were significantly more abundant than males, and had asynchronous oocyte development both within and among individuals. Male anemones showed a single annual cycle of spermary growth, development and spawning. Data from the 26-month study indicated that spawning occurred in the austral summer and autumn between January and April, which coincided with the observed spawning periods that have previously been documented for this species in outdoor flow-through seawater tanks at the study location. The biopsy sampling technique used during this study provides an opportunity to gain a more thorough understanding of the gametogenic cycles and sexual pattern of host sea anemones throughout their distribution.

 

[ThRoewer]

Related to post #7

Social and mating systems of the protandrous anemonefish Amphiprion perideraion under the influence of a larger congener Full PDF

Abstract:
The effect of a larger anemonefish Amphiprion clarkii (Bennett) on the social and mating system of a smaller congener Amphiprion perideraion (Bleeker) was investigated on a coral reef at Okinawa, Japan, where both species use the same host sea anemone Heteractis crispa (Ehrenberg). The population of A. perideraion consisted of adult, subadult and juvenile groups. Adult groups, which consisted of one or two adults and a varying number of subadults and juveniles, usually did not share the host with A. clarkii. In contrast, subadult and juvenile groups, which included no adults, always cohabited with A. clarkii. In the heterospecific groups, subadult A. perideraion were able to mature histologically, and changed to female when they were the largest among conspecific members, although their reproduction was suppressed by A. clarkii. After all members of A. clarkii emigrated or disappeared from a heterospecific group, adult A. perideraion could begin breeding. I suggest that A. perideraion in both heterospecific and conspecific groups adopt a mating strategy that involves waiting for vacated breeding posts because of their low mobility and a low host density.

 

[Evolve29]

I was hoping you would share this article So in theory, we could make captive bred clowns accepting of all host anemones, assuming their parents could be made to accept an unnatural host.

I got a orange blood clownfish that loves any anemones from its current fav, a Condy to. Last night, I took a peek into the tank with lights off, she was near a flower anemone huddled next to the base though. I haven't seen any clowns host flowers but this one doesn't seem to be affected now. Use to when brushed on it tentacles, it would get stung and swim away. Now I noticed that when she brushes against the flower, she doesn't seem to feel anything.

I do wish the the male would pair up with female. She has chased him away from anemone, no signs of other aggression other than that such as fin biting or such.

 

[ThRoewer]

Host specialist clownfishes are environmental niche generalists (Full PDF)

Abstract

Why generalist and specialist species coexist in nature is a question that has interested evolutionary biologists for a long time. While the coexistence of specialists and generalists exploiting resources on a single ecological dimension has been theoretically and empirically explored, biological systems with multiple resource dimensions (e.g. trophic, ecological) are less well understood. Yet, such systems may provide an alternative to the classical theory of stable evolutionary coexistence of generalist and specialist species on a single resource dimension. We explore such systems and the potential trade-offs between different resource dimensions in clownfishes. All species of this iconic clade are obligate mutualists with sea anemones yet show interspecific variation in anemone host specificity. Moreover, clownfishes developed variable environmental specialization across their distribution. In this study, we test for the existence of a relationship between host-specificity (number of anemones associated with a clownfish species) and environmental-specificity (expressed as the size of the ecological niche breadth across climatic gradients). We find a negative correlation between host range and environmental specificities in temperature, salinity and pH, probably indicating a trade-off between both types of specialization forcing species to specialize only in a single direction. Trade-offs in a multi-dimensional resource space could be a novel way of explaining the coexistence of generalist and specialists.

 

[ThRoewer]

An extraordinary life span estimate for the clown anemonefish Amphiprion percula (Full PDF)

Abstract

A population of the clown anemonefish Amphiprion percula was studied for 1 year, in Madang Lagoon, Papua New Guinea. From this study, data on mortality events and social structure were used to construct a stage-structured matrix model and estimate the average age at death (life expectancy) of various classes of individuals. Based on this model, it is estimated that the life expectancy of female A. percula, the oldest individuals in the population, is 30 years. This estimate is two times greater than the longevity estimated for any other coral reef damselfish and six times greater than the longevity expected for a fish of that size. The result complements the growing body of evidence, from widespread taxa, that organisms subject to low levels of extrinsic mortality show retarded senescence and increased longevity. It is suggested that fishes would be an excellent group for a broad scale comparative test of the predictions of the evolutionary theory of ageing.

 

[ThRoewer]

Highly restricted gene flow between disjunct populations of the skunk clownfish (Amphiprion akallopisos) in the Indian Ocean (Full PDF)

Abstract

The skunk clownfish (Amphiprion akallopisos) has a disjunct distribution, occurring in the Eastern Indian Ocean (EIO) and the Western Indian Ocean (WIO), separated by several thousands of kilometres. Information on connectivity of marine species is very important for the correct spacing of marine protected areas, a powerful instrument for the protection of coral reefs. The population genetic structure of A. akallopisos was analysed in order to investigate connectivity amongst populations and to explain the disjunct distribution of the species. A fragment of the mitochondrial control region was used to investigate the genetic population structure. Fin clips were collected from 263 individuals at 14 sites in the WIO and three sites in the EIO. The obtained DNA sequences were used to calculate genetic diversity, evaluate demographic history and to construct a haplotype network. An analysis of molecular variance (AMOVA) was conducted to evaluate the significance of the observed genetic population structure. None of the identified 69 haplotypes was shared between the WIO and EIO. Haplotype as well as nucleotide diversity was considerably higher in the EIO than in the WIO. Significant genetic population structure was revealed by an AMOVA with an overall φst-value of 0.28 (P < 0.001) in the Indian Ocean. The overall AMOVA (φst = −0.00652) was not significant in the EIO, but was significant in the WIO (φst = 0.016; P < 0.01). Demographic analysis indicated population expansion in the EIO and WIO. Population genetic analysis revealed highly restricted gene flow between the EIO and WIO. Genetic diversity was much higher in the EIO than in the WIO, suggesting that the EIO is the geographical origin of the species. Given the large distance between the disjunct populations and the short pelagic larval duration, long-distance dispersal is rather unlikely. A stepping stone model involving islands in the Central Indian Ocean is a more likely scenario for colonization of the WIO.

 

[ThRoewer]

Analysis of the coding sequences of clownfish reveals molecular convergence in the evolution of lifespan (Full PDF)

Abstract
Background: Standard evolutionary theories of aging postulate that reduced extrinsic mortality leads to evolution of longevity. Clownfishes of the genus Amphiprion live in a symbiotic relationship with sea anemones that provide protection from predators. We performed a survey and identified at least two species with a lifespan of over 20 years. Given their small size and ease of captive reproduction, clownfish lend themselves as experimental models of exceptional longevity. To identify genetic correlates of exceptional longevity, we sequenced the transcriptomes of Amphiprion percula and A. clarkii and performed a scan for positively-selected genes (PSGs).
Results: The PSGs that we identified in the last common clownfish ancestor were compared with PSGs detected in long-lived mole rats and short-lived killifishes revealing convergent evolution in processes such as mitochondrial biogenesis. Among individual genes, the Mitochondrial Transcription Termination Factor 1 (MTERF1), was positivelyselected in all three clades, whereas the Glutathione S-Transferase Kappa 1 (GSTK1) was under positive selection in two independent clades. For the latter, homology modelling strongly suggested that positive selection targeted enzymatically important residues.
Conclusions: These results indicate that specific pathways were recruited in independent lineages evolving an exceptionally extended or shortened lifespan and point to mito-nuclear balance as a key factor.
Keywords: Amphiprion, Positive selection, Evolution of lifespan, Life-history trait, Mito-nuclear balance