10.5061/DRYAD.2280GB5TF
Morales-Saldaña, Saddan
0000-0001-6844-356X
National Autonomous University of Mexico
Oyama, Ken
National Autonomous University of Mexico
Valencia Ávalos, Susana
0000-0003-4017-2387
National Autonomous University of Mexico
Tovar Sánchez, Efraín
0000-0001-7152-7924
Universidad Autónoma del Estado de Morelos
Hipp, Andrew
0000-0002-1241-9904
Morton Arboretum
González Rodríguez, Antonio
National Autonomous University of Mexico
Even more oak species in Mexico? Genetic structure and morphological
differentiation support the presence of at least two specific entities
within Quercus laeta
Dryad
dataset
2021
FOS: Biological sciences
genetic differentiation
Gene flow
leaf morphometrics
Microsatellite loci
morphotype
population assingment
Species delimitation
Consejo Nacional de Humanidades, Ciencias y Tecnologías
https://ror.org/059ex5q34
483720 / 624511
PAPIIT-DGAPA-UNAM*
210020
Instituto de Investigaciones en Ecosistemas y Sustentabilidad*
2021-12-14T00:00:00Z
2021-12-14T00:00:00Z
en
29272 bytes
3
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Differentiation among populations, sometimes despite ongoing gene
exchange, is a key step in speciation. Therefore, comparison of intra- and
interspecific differentiation patterns is of great significance to
understanding speciation. The genus Quercus is an interesting system to
test speciation models in the presence of gene flow, due to its weak
interspecific reproductive barriers. The aim of the present study was to
characterize the degree and pattern of morphological and genetic
differentiation among different morphotypes in the white oak Quercus
laeta, some corresponding to the previously described species Q.
centralis, Q. laeta, Q. prinopsis and Q. transmontana, as well as
geographically structured variation within Q. transmontana not previously
described. Our goal was to evaluate if some of these can be considered
distinct specific entities or are rather part of a continuum of variation.
Nine microsatellite loci and two intergenic regions of chloroplast DNA
were analyzed. Morphological differences were evaluated using geometric
morphometrics. Chloroplast DNA showed low differentiation, suggesting
introgression or sharing of ancestral haplotypes among the Q. laeta
morphotypes. Nuclear microsatellites indicated differentiation into two
distinct main genetic groups, which were congruent with morphological
differentiation. In conclusion, nuclear markers and morphological
variation suggest the existence of at least two different entities within
Q. laeta.
A total of 161 adult individuals of the Q.
laeta complex were sampled from 19 sites (hereafter, ‘populations’ refers
to samples from these locations as geographically defined, unless
otherwise specified). At each population, 5-11 randomly selected
trees were sampled, separated from each other by a minimum of 30-50
m. Populations almost covered the complete geographical distribution of Q.
laeta and the five morphotypes. At each site, the trees were
identified based on the above-mentioned diagnostic morphological
characters. Collected branches were pressed and dried to obtain three
herbarium specimens. From each tree, we additionally sampled mature
leaves with no apparent damage from different branches; these leaves were
stored in plastic bags and placed on ice until final storage at -80 °C in
the laboratory for genetic analysis. Likewise, between six and
eight mature leaves were pressed per individual for the corresponding
morphometric analyses. Vouchers of specimens were deposited in
the FCME herbarium. To estimate the population genetic diversity and
structure, nine nuclear microsatellite loci were amplified in three
multiplex PCRs and two individual reactions. The first multiplex reaction
included the QpZAG96 and QpZAG110 loci; the second the QpZAG36 and
QrZAG39 loci and the third the quru-GA-IF02, quru-GA-OC11 and
quru-GA-OMO5 loci. Finally, the quru-GA-OC19 and quru-GA-2F05 loci were
amplified separately. Reactions were carried out with 3 µL of Taq-Platinum
master mix (Qiagen CA, USA), 0.3 µL of each forward and reverse
primer (0.2 µM), 1.4 µL of H2O, and 1 µL of genomic DNA (10 ng/ µL) in a
total volume of 6 µL. The reaction began with 3 min denaturation at 94 °C,
followed by 40 cycles of 30 s denaturation at 94 °C, 45 s annealing at
54 °C for quru-GA-OC19 and the first and third multiplex reactions, 48°C
for the second multiplex reaction and 45 °C for quru-GA-OM05. A final
extension step of 10 min at 72 °C was included. One µL of each PCR product
was combined with 9 µL of Hi-Di Formamide and 0.3 µL of GeneScan-600 LIZ
(Applied Biosystems, CA, USA) and run on an ABI-PRISM 3100-Avant sequencer
(Applied Biosystems, CA, USA) to obtain the size of the microsatellite
fragments. Electropherograms were analyzed
using the GENEMARKER software v.1.91 (Softgenetics LLC, State College, PA,
USA). The individual genotype assignments of the nine nSSR were verified
at least three times to corroborate our genotyping.
Missing data = 0