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- Five sea turtle species occur in Brazil
Background
Dermocheliidae
Photos: Projeto Tamar
Hawksbill x loggerhead hybrids at Brazilian feeding grounds Mara - - PowerPoint PPT Presentation
Hawksbill x loggerhead hybrids at Brazilian feeding grounds Mara - - PowerPoint PPT Presentation
Hawksbill x loggerhead hybrids at Brazilian feeding grounds Mara Proietti, Cntia Brito, Ana Figueiredo, Rodrigo Maggioni, Danielle Monteiro, Julia Reisser Background Five sea turtle species occur in Brazil Dermocheliidae Cheloniidae
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- Threats include poaching, habitat loss/alteration, bycatch,
and marine debris
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- Hybridization: possible threat to Brazilian sea turtles?
- Hybridization between
Cheloniids has been reported worldwide
Photos: Projeto Tamar
Background
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- Brazil: very high rates in BA/SE
- Possible causes: large pop.
reductions, spatial-temporal
- verlap, skewed sex ratios
- Consequences?
BA ¡ 27% 42%
Reis et al. 2010 Lara-Ruiz et al. 2006
SE ¡
Background
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- Bahia rookery: 42% “hawksbill” females are hybrids
Lara-Ruiz et. al. 2006
X ¡
Morphology mtDNA
Background
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- Female hybrids lay viable eggs
X
Morfology mtDNA
=
Until recently, no
- bservation of
immature hybrids from BA at FGs
Background
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To fill this gap
Skin samples - 224 immature hawksbills
Blumenthal ¡et ¡al. ¡2009 ¡ n=56
n=72 n=55 n=6
n=24
n=12
800 bp mtDNA D-loop (Abreu-Gobrois et al. 2006) Amplification/sequencing Sequence analysis/ haplotype id
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¡ ¡
- Eight turtles (37 to 52 cm CCL): Hawksbill morphology but
Loggerhead mtDNA (Bahia haplotype)
Results
CC-A4 ¡
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¡ ¡
Results
Núcleo de Educação e Monitoramento Ambiental
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¡ ¡
Results
Immature hybrid distribution
CE: 1/56 RS: 6/24
BA ¡
BA: 1/55
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¡ ¡
- Dispersal to the South – favored by currents?
Results
BA ¡
RS: 6/24
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¡ ¡
- Particle dispersal model (ICHTHYOP 3.2)
- 3 simulations according to peak hatching period
- Temporal overlap, but slightly distinct peaks
Jan Loggerheads Hawksbills Mar Apr Nov May Hybrids
Results
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¡ ¡
Loggerheads – 72% S Hybrids – 44% S Hawksbills – 36% S
Proietti et al. 2014
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Hawksbill: Tropical, coastal Not common in South BR
Loggerhead: Wider distribution High occurrence in South BR
Results
- Dispersal to the South – ecological/behavioral?
seaturtleexploration.com
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¡ ¡
Next steps
X ¡
Morphology mtDNA
- Until now: only mtDNA
Allows hybrid detection only when morphology/mtDNA are different
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¡ ¡
Next steps
nDNA analyses
(markers described by Vilaça et al. 2012)
Can detect hybrids even when morphology and mtDNA are the same Provides more info – parental species, generations, signs of introgression Additional sampling (more coverage!)
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What we expect...
- Increase the detection of immature hybrid turtles in Brazil;
- Better understand the distribution patterns of hybrids
along the coast;
- Evaluate the characteristics of this hybridization
(generations, parental species);
- Collaborate with other projects studying hybrids to help
diagnose the effects of hybridization on endangered sea turtle species in Brazil.
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