LOGIN

RSS Facebook Twitter YouTube
GLOSSARY       

SEARCHGLOSSARY

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

PROFILESEARCH

Avatar

Please consider registering
guest

sp_LogInOut Log In sp_Registration Register

Register | Lost password?
Advanced Search

— Forum Scope —




— Match —





— Forum Options —





 

Minimum search word length is 4 characters - maximum search word length is 84 characters

sp_Feed Topic RSS sp_TopicIcon
Journal of Morphology - early view
January 28, 2014
2:54 pm
Avatar
Matt
Málaga, Spain
Admin
Forum Posts: 8239
Member Since:
June 13, 2011
sp_UserOfflineSmall Offline

Comparative development and evolution of two lateral line phenotypes in lake malawi cichlids

A comparison of the pattern and timing of development of cranial lateral line canals and canal neuromasts in three species of Lake Malawi cichlids, Labeotropheus fuelleborni and Metriaclima zebra (narrow lateral line canals), and Aulonocara baenschi (widened lateral line canals) was used to test the hypothesis that the evolution of widened canals (thought to be an adaptive phenotype in the lateral line system) from narrow canals is the result of heterochrony. Using histological analysis and scanning electron microscopy, this study has provided the first detailed and quantitative description of the development of widened lateral line canals in a teleost, and has demonstrated that: 1) canal neuromast number and the pattern of canal morphogenesis are conserved among species with different adult canal phenotypes, 2) heterochrony (“dissociated heterochrony” in particular) can explain the evolution of widened canals and variation in morphology between canals within a species with respect to canal diameter and neuromast size, and 3) the morphology of the lateral line canals and the dermal bones in which they are found (e.g., the mandibular canal the dentary and anguloarticular bones of the mandible) can evolve independently of each other, thus requiring the addition of another level of complexity to discussions of modularity and integration in the skull of bony fishes

Morphometric variation between two morphotypes within the Astyanax Baird and Girard, 1854 (Actinopterygii: Characidae) genus, from a Mexican tropical lake

Phenotypic variation is important for evolutionary processes because it can allow local adaptation, promote genetic segregation, and ultimately give rise to speciation. Lacustrine systems provide a unique opportunity to study the mechanisms by which sister species can co-occur by means of ecological segregation. The fish genus Astyanax is characterized by high levels of phenotypic variability, providing an excellent model for the study of local specialization. Here, we analyze the morphological specializations through geometric morphometrics of two sympatric species described as different genera: Bramocharax caballeroi endemic to Lake Catemaco, and the widely distributed Astyanax aeneus. Additionally, we assess the correlation between phenotypic and genetic structure, and the phylogenetic signal of morphological variation. We examined body size and shape variation in 196 individuals and analyzed mitochondrial cytochrome b sequences in 298 individuals. Our results confirm the striking morphological divergence among the sympatric characids. Differences between them were mainly found in the body depth and profile and orientation of the head, where B. caballeroi in contrast with the A. aeneus, presented a fusiform body and an upward mouth. Moreover, different growth trajectories were observed among morphotypes, suggesting that a heterochronic process could be involved in the diversification of our study system. Morphological differences did not correspond with the molecular differentiation, suggesting high levels of homoplasy among the lineages of B. caballeroimorphs.

Cake or death?
Forum Timezone: Europe/Paris

Most Users Ever Online: 246

Currently Online:
1 Guest(s)

Currently Browsing this Page:
1 Guest(s)

Devices in use: Desktop (1)

Top Posters:

Stefan: 1567

Plaamoo: 1253

mikev: 1134

Malti: 1099

Mark Duffill: 1012

Member Stats:

Guest Posters: 0

Members: 30280

Moderators: 0

Admins: 2

Forum Stats:

Groups: 4

Forums: 10

Topics: 4595

Posts: 36614

Newest Members: cassman66, crabhappy, StygianSteel, marcelmueller, foreverlearning

Administrators: dunc: 1323, Matt: 8239