Which cranial view (dorsal, ventral, lateral or occipital) best reflects phylogenetic relationships among five European grayling (Thymallus thymallus) populations?
2016
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Authors:
Bajić, AleksandarMarić, Saša
Miljanović, Branko
Snoj, Aleš
Askeyev, Oleg
Askeyev, Igor
Jojić, Vida
Document Type:
Conference object (Published version)
,
© 2016 by the Macedonian Ecological Society
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Show full item recordAbstract:
The European grayling, Thymallus thymallus (Linnaeus, 1758) is salmonid fish species with
complex life history depicted mostly by recent genetic research. As a result, at least five major
phylogenetic lineages have been described and fine genetic structure in each of the lineages has
been discovered. Herein, we analyzed cranial morphology of T. thymallus from three different basins
that correspond to three previously described phylogenetic lineages. Landmark-based geometric
morphometric methods were applied to four cranial views (dorsal, ventral, lateral and occipital). We
used specimens from five European grayling populations (Adriatic Sea – Soča River, Black Sea – Sava
Bohinjka and Una Rivers, Caspian Sea – Bugurla and Kana Rivers). Cranial size analyses revealed
significant size differences for all pairwise comparisons (dorsal cranium: P<0.05; ventral cranium:
P<0.01; lateral cranium: P<0.05; occipital cranium: P<0.05). When comparing centroid sizes (CS) for
all four views, Soča population had the largest mean values, while Bugurla population had the smallest
values of centroid size means. Significant interaction between log CS and population was revealed
only for ventral cranium (λWilks=0.1454, F92,232.07=1.58, P=0.0031). Therefore, Canonical variate analysis
(CVA) of inter-population ventral cranial shape differences was conducted without correction for the
allometry. For the other three cranial perspectives, CVA of non-allometric shape variation showed
best separation of studied populations at the level of occipital cranium. Namely, populations from
the same basin were grouped more tightly, while Soča population was separated from the other four
populations. Specimens from Caspian Sea basin showed overall flattening of the cranium in occipital
view. In individuals from Soča population dorsal base of supraoccipital crest was moved more dorsally,
resulting in higher skull with pronounced supraoccipital crest. Most of the landmarks digitized on
occipital cranium were located on neurocranial skeletal elements that are generally considered more
conservative and thus gave best reflection of phylogenetic relationships.
Keywords:
Salmonidae; Geometric morphometrics; Allometry; morphology; shape; Skull; sizeFunding / projects:
- Genetic and phenetic diversity in natural populations across different environments - contribution of B chromosome polymorphism (RS-MESTD-Basic Research (BR or ON)-173003)
In:
- 5th Congress of ecologists of the Republic of Macedonia with international participation: Abstract book; 2016 Oct 19-22; Ohrid, Republic of Macedonia. Skopje: Macedonian Ecological Society; 2016. p. 34.