Developmental changes through an animal’s life are generally understood to contribute to the resulting adult morphology. A possible exception are species with complex life cycles, where individuals pass through distinct ecological and morphological life stages during their ontogeny, ending with metamorphosis to the adult form. Antagonistic selection is expected to drive low genetic correlations between life stages, theoretically permitting stages to evolve independently. Using the Australian frog radiation, we examine the evolutionary consequences on morphological evolution when life stages are under different selective pressures. We use morphometrics to characterise body shape of tadpoles and adults across 166 species of frog and investigate similarities in the two resulting morphological spaces (morphospaces) to test for concerted evolution across metamorphosis in trait variation during speciation. A clear pattern emerges: Australian frogs and their tadpoles are evolving independently; their drastically different morphospaces and contrasting estimated evolutionary histories of body shape diversification indicate that different processes are driving morphological diversification at each stage. Tadpole morphospace is characterised by rampant homoplasy, convergent evolution and high lineage density; the adult morphospace by contrast shows greater phylogenetic signal, low lineage density and divergent evolution between the main clades. Our results provide insight into the macroevolutionary consequences of a biphasic life cycle.
R code
R code to perform all the analyses
Supplementary data file 1
Adult body shape data for 166 species. Linear measurements for characterizing the body shape of adult frogs. 1
SVL
From tip of the snout to posterior tip of the urostyle
2
Head_l
From tip of snout to angle of jaw
3
Head_width
Width of head right behind the eyes
4
Eye_naris
From anterior corner of eye to posterior edge of naris
5
Interorbital
Distance between anterior corners of eyes
6
Internarial
Distance between inner edges of nares
7
Naris_Snout
Distance between anterior edge of naris and tip of the snout
8
Eye_l
Distance between corners of eye (anterior to posterior)
9
Mouth_width
Width of the head right between corners of the mouth
10
Humerus_l
Distance between midpart of the pectoral girdle and elbow
11
Forearm_l
Distance between elbow and wrist
12
Wrist_width
Width of the wrist on its widest point
13
Hand_l
Distance between the midpart of the wrist and the tip of the 3rd finger
14
Thumb
Thumb length
15
Finger_4
4th finger length
16
Femur_l
Distance between the midpart of the urostyle and the knee
17
Femur_width
Maximum width of the femur (midpart)
18
Tibial_l
Knee to heel (tibiofibular)
19
Tibial_width
Maximum width of the tibia (midpart)
20
Foot_l_toe_1
Distance from base of 1st toe to tip of 4th toe
21
Foot_l_total
Distance from heel to tip of 4th toe
22
Toe_1
Length of 1st toe (from tip to join between 1st and 2nd toe)
23
Toe_5
Length of 5th toe (from tip to join between 4th and 5th toe)
Supplementary data file 2
Tadpole body shape data for 166 species. Landmarks and semilandmarks for characterizing the body shape of tadpoles. 1
Centre of the eye
2
Centre of the external nares
3
Point where the upper labium contacts the head/body
4
Point where the lower labium contacts the head/body
5
Intersection of the head/body and tail on the ventral side, anterior to the vent
6
Intersection of the ventral edge if the tail muscle and the head/body
7
Intersection of the dorsal edge if the tail muscle and the head/body
8
Tip of the tail
9
Point on the dorsal fin closest to landmark 7 (superficially denotes the intersection of the head/body and tail regions)
10 to 17
Equally-spaced semilandmarks marking the curve of the dorsal aspect of the head/body when viewed laterally
18 to 27
Equally-spaced semilandmarks marking the curve of the dorsal aspect of the tail fin when viewed laterally
28 to 37
Equally-spaced semilandmarks marking the curve of the ventral aspect of the tail fin when viewed laterally
38-45
Equally-spaced semilandmarks marking the curve of the ventral aspect of the head/body when viewed laterally
46 to 55
Equally-spaced semilandmarks marking the curve of the notochord
Supplementary data file 3
Tadpole body size data. Centroid size of tadpoles.
Supplementary data file 4
Phylogenetic tree of 166 species
Supplementary data file 5
Classifier file with meta information for all 166 species in this study