No. 26
Chao-Qun Li, Tian-Feng Lü, Meng-Qi Han, Yang Dong, Peng-Wei Li, Yan Liu, and Yin-Zheng Wang
Reversal versus specialization in floral
morphological evolution in Petrocosmea (Gesneriaceae) & some new taxa
of Petrocosmea
Journal of Systematics and Evolution:
Accepted Article
ORCID iD: 0000-0002-3113-2650
https://doi.org/10.1111/jse.12541
Abstract
A
widely held hypothesis in evolution is that adaptive specialization constrains the potential direction of future evolutionary
change and thus may be irreversible, i.e.,
the Dollo’s law. However, this hypothesis has long been subject to debate in evolutionary biology. Floral specialization is
intriguing as it is usually linked to reproductive
isolation and may affect speciation. Here, following the discovery of four new taxa, we observed some interesting
phenomena of reversal versus specialization
in morphology in a clade with the most specialized flowers in the genus Petrocosmea.
In the phylogenetic tree based on sequences of multiple DNA regions, the morphological reversals, especially
the regain of a long corolla-tube, are
nested within the branches characteristic of normally specialized flowers with short corolla tube and highly specialized
zygomorphy. Our results demonstrate that
the highly specialized floral organ of this clade is still actively evolving in multiple branches toward specialization while
reversals to different ancestral states occur in some branches. The great
disturbance of ecological environment is likely a crucial factor affecting trait reversibility, such as the
rapid uplift of the Himalaya-Tibet
plateau. The four new taxa are treated herein taxonomically. The flowers of this clade represent an interesting
model to explore the genetic basis underlying
the evolutionary reversal versus specialization and the interplay between genetic factors and environmental
variables.
Original Link:https://onlinelibrary.wiley.com/doi/abs/10.1111/jse.12541

Fig.
1. The most
parsimonious tree and photos of flowers of corresponding taxa.The most
parsimonious tree (left) is generated from combined cpDNA and nuclear DNA data. Photos of flowers are the
corresponding taxa (bold faces indicate
the new taxa) sampled in the phylogenetic analysis (right). Bootstrap (BS) values are on the left side of the slash
and Bayesian posterior probabilities (PP)
on the right. 1-2, outgroups, 1, Raphiocarpus petelotii, 2, R. begoniifolius; 3-6, species of clade A, 3-4, P. grandifolia, face (3) and lateral (4) view, 5-6, P. menglianensis,
face (5) and lateral (6) view; 7-10, species
of clade B, 7-8, P. sichuanensis, face (7) and lateral (8) view, 9-10, P. intraglabra, face (9) and lateral
(10) view; 11-38, species of clade
C, including four new taxa, 11-12, P.huanjiangensis, face (11) and lateral (12) view, 13-14, P. xingyiensis, face (13) and
lateral (14) view, 15-16, P. shilinensis, face (15) and lateral (16) view, 17-18, new
variety P.
shilinensis var. changhuensis, face (17) and lateral (18) view, 19-20,
P. minor, face (19) and lateral (20) view. 21-22, new species P. purpureoglandulosa, face (21) and lateral (22) view, 23-24, P. iodioides, face (23) and
lateral (24) view, 25-26, P. leiandra, face (25) and lateral (26) view, 27-28, new
species P.
longituba, face
(27) and lateral (28) view, 29-30, new
species P. qionglaiensis, face (29) and lateral (30) view, 31-32, P. martinii, face (31) and lateral
(32) view, 33-34, P. sericea, face (33) and lateral (34) view, 35-36, P. yanshanensis, face (35) and lateral (36) view, 37-38, P. grandiflora,
face (37) and lateral (38) view; 39-42, species of clade D, 39-40,
P.
barbata, face
(39) and lateral
(40) view, 41-42, P. cavaleriei, face (41) and lateral (42) view; 43-46, species of clade E, 43-44, P. oblata, face (43) and lateral (44)
view, 45-46, sinensis, face (45) and lateral (46) view. (15-16 Photos
taken by Shui YM)

Fig.
2. Photos of P. shilinensis var. changhuensis with comparison of P. shilinensis. 1-7.
P. shilinensis var.
changhuensis. 1. Habitat. 2, 3. Plants
with basal
leaves. 4. Flower of face view,
showing two white oblong stripes extended to the throat on abaxial corolla lip. 5. Flower of side view. 6. Stamen, showing filaments white. 7. Leaf, showing leaf rhombic, margin crenate, base cuneate, lateral veins abaxially conspicuous. 8-11. P. shilinensis. 8. Flower
of face view, showing
several white stripes on the inner surface of abaxial side of corolla restricted in the tube. 9. Flower of side view. 10. Stamen,
showing filaments purple.
11. Leaf, showing leaf cordate, base
cordate, margin serrulate, lateral veins abaxially unconspicuous. (8-11. Photos taken by Shui YM.)

Fig.
3. Photos of P. purpureoglandulosa with comparison of
P. minor. 1-6. P. purpureoglandulosa. 1. Habitat.
2. Plants with basal leaves. 3. Flower of face view. 4. Flower
of side view, showing the carinate-plicate structure straight on the adaxial side. 5. Abaxial corolla
lip, showing lateral lobs broad ovate and two little round brown spots on the inner surface of
corolla tube below filaments. 6. Stamen, showing filaments slightly curved, densely purple
glandular. 7-11. P. minor. 7. Plants with basal
leaves. 8. Flower of face view. 9. Flower of side view, showing the carinate-plicate structure
protuberance on the adaxial side. 10. Abaxial corolla lip, showing lateral lobes triangular and two big
triangular brown spots on the inner surface of corolla tube below filaments. 11. Stamen, showing filaments strongly geniculate, densely white
glandular.

Fig.
4. Photos of P. qionglaiensis, P. longituba with comparison of P.
iodioides and P.
leiandra. 1-4. P. qionglaiensis. 1, 2. Habitat, growing on the moist shady cliff of the limestone hill. 3, 4. Plants with basal leaves. 5-8. P. longituba. 5, 6. Habitat, growing on the moist shady cliff of the limestone hill. 7, 8. Plants
with basal
leaves. 9-13. P. iodioides. 9. Face
view. 10. Top view. 11. Side view. 12. Stamen. 13.
Leaf. 14-18. P. leiandra. 14. Face view. 15. Top
view. 16. Side view. 17. Stamen. 18. Leaf. 19-23. P. longituba. 19. Face view. 20. Top
view. 21. Side view. 22.
Stamen. 23. Leaf. 24-28. P. qionglaiensis. 24. Face
view. 25. Top view. 26.
Side view. 27. Stamen. 28. Leaf, showing petiole dark red-brown.

Fig.
5. Tube length
divergence in Petrocosmea. X-axis:
species of Petrocosmea; Y-axis: relative tube length (R (tube)). Line of 30% on Y axis was set
to better shown
the difference between species with long tube and short tube. 30% is the average value of relative tube length (R
(tube)).
Those
new taxa of Petrocosmea from China in this article
1. 长湖石蝴蝶 Petrocosmea
shilinensis Y. M. Shui & H. T. Zhao var. changhuensis T.
F. Lü & Y. Z. Wang var. nov.
2. 紫腺石蝴蝶 Petrocosmea purpureoglandulosa Y. Dong
& Y. Z. Wang sp. nov.
3. 长筒石蝴蝶
Petrocosmea longituba M. Q. Han & Yan Liu sp. nov.
4. 邛崃石蝴蝶
Petrocosmea qionglaiensis C. Q. Li & Y. Z. Wang sp. nov.
All
figures and information of above-mentioned new taxa of Petrocosmea were
showed in the listed colorful figures