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Phylogeographic patterns in four species of Ctenomys in south Brazil

(Rodentia-Octodontidae)

Thales Renato O. de Freitas

Departamento de Genética

UFRGS

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• About 60 described species

• Species occur in the meridional region of Neotropic in Patagonian subregion

• Occupy sand fields

• Quick speciation – 3My

• High chromossomic variation (2n = 10 – 70)

Ctenomys

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• Popular name: Tuco-tuco

• Subterranean rodents

• Physiology and morphology are adapted to subterranean niche

Ctenomys

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Ctenomys torquatus Ctenomys flamarioniCtenomys lami

Ctenomys minutus

Ctenomys in RS and SC

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2n=46

8 acrocentrics

14 metacentrics

2n=44

6 acrocentrics

15 metacentrics

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Ctenomys torquatus: geographic distribution

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Haplotype network

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Haplotype distribution

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P < 0,05 for all comparisons

Population differentiation- Fst

Butiá-Minas do Leão: 9km

Cachoeira-Rio Grande: 206km

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Microsatellites data from Ctenomys torquatus - Structure

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• Color is almost white

• Live in first line of sand dunes

• 2n=48

Ctenomys flamarioni

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Photos: J.F. Stolz e M. Mora

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Sample

•N=154 animals;

•10 populations: 4 blocks

I: Xangri-lá, Remanso

II: Pinhal, S. Simão

III: Bujurú, S. José do Norte

IV: Cassino, Taim e Chuí

Phylogeography

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Phylogenetic reconstruction

Neighbour-joining, using PAUP 4.0 (Swofford 2002)

Regions I + II + III

Region IV

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Conservation• Phylogeographic patterns

+

• Enzimatic polymorphism and chromosomic differences

Evolutionary significative units: (ESUs)

1. Regions I + II + III

2. Region IV

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Ctenomys minutus

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Chromosomic variation: chromosomic rearrangements found in C. minutus

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Chromossomic variation

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Molecular variation

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Network concatenado

CR + COI

Haplotypes sharing different karyotypes (Karyotypes do not work as reproductive barriers)

6 genetic groups

• North - Araranguá

• Litoral – sand dunes

• Barros Lake- ?

• Mostardas – Paleocanal Jacuí

• Tavares – Paleocanal Camaquã

• South

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• From Farol de Santa Marta (SC) to São José do Norte (RS)

• Linear distribution(sand fields and dunes)

• 2n=42 to 2n=50 (45 karyotypes - 6 HZ)

• 2 rivers and 2 paleochannels

Ctenomys minutus

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Ctenomys lami

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• Coxilha das Lombas region

(78km x 12km

• Linear distribution (1st

barrier)

• 2n = 54 to 58

• 26 karyotypes

• 4 population blocks

• 2 hybrid zones

• 55a/56a x 58 = 57

• 54 x 56b = 55b

• Swamp between B and C

blocks

Ctenomys lami

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Concatenated network CR + COI (C. lami)

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Network in C. lami

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Hybrid zone between C. lami and C. minutus

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Collection points in hybrid zone between C. lami and C. minutus

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Chromosomic comparison betweenC. lami and C. minutus

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C. minutus + C. lami + hybrids

•Karyotypes are not reproductive barriers

• Intraspecific hybrids and parental forms share

haplotypes

•In the past (1970) both species were separated

by river and swamp

• Dados concatenados Bayesiana

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• Data concatenated by Bayesian

• 5 genetic groups in C. minutus due to geography (rivers, paleochannels, transition (field/dune)

• 2 groups in C. lami

• Block D does not share haplotypes with C. minutus neither with hybrids

• Haplotypes from A, B, and C groups together with the lineage from Lagoa dos Barros

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• C. lami and C. minutus share haplotypes

• All hybrids share haplotypes with C.

minutus

• Females of C. minutus mating with males of

C. lami and having hybrids

• Females of C. lami mate with males of C.

minutus generating infertile individuals

• Dados concatenados Bayesiana

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Ctenomys torquatus Ctenomys flamarioniCtenomys lami

Ctenomys minutus

Ctenomys in RS and SC

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Apoio: CNPq, FAPERGS,

PROPESQ/UFRGS

Fundação O Boticário

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