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Phenotypictraits have been shown to evolve in response to variation in the environment. However, the evolutionary processes underlying the emergence of phenotypic diversity can typically only be understood at the population level. Consequently, how subtle phenotypic differences at the intraspecific level can give rise to larger-scale changes in performance and ecology remains poorly understood. We here tested for the covariation between ecology, bite force, jaw muscle architecture, and the three-dimensional shape of the cranium and mandible in 16 insular populations of the lizards Podarcis melisellensis and P. sicula. We then compared the patterns observed at the among-population level with those observed at the interspecific level. We found that three-dimensional head shape as well as jaw musculature evolve similarly under similar ecological circumstances. Depending on the type of food consumed or on the level of sexual competition, different muscle groups were more developed and appeared to underlie changes in cranium and mandible shape. Our findings show that the local selective regimes are primary drivers of phenotypic variation resulting in predictable patterns of form and function. Moreover, intraspecific patterns of variation were generally consistent with those at the interspecific level, suggesting that microevolutionary variation may translate into macroevolutionary patterns of ecomorphological diversity., (© 2021 The Authors. Evolution © 2021 The Society for the Study of Evolution.)

The objective of the present study was to assess if cervical ripeness could be quantified by measuring the percentage of denaturation of the collagen network of the stromal layer. Biopsy specimens from the caudal part of the cervix were obtained from nine pluriparous cows between Days 149 and 157 of gestation (second-trimester biopsy), at exactly Day 275 of gestation (term biopsy), and shortly after calving (calving biopsy). The samples were divided into a superficial stromal part and a deep stromal part. The water content was derived from the weight of the samples before and after lyophilization. A colorimetric assay was used to assess the percentage of collagen denaturation by determining the extinction at 570 nm of hydroxyproline released from alpha-chymotrypsine-treated samples. By incorporating a hydroxyproline standard series in the measurements, the insoluble collagen content (mug/mg dry wt) as well as the insoluble collagen concentration (mug/mg wet wt) could be derived. The water content of both layers of the cervix significantly increased between midpregnancy and parturition (P < 0.01). The insoluble collagen content and the insoluble collagen concentration were significantly increased at term (P < 0.01 and P < 0.05, respectively) but were significantly decreased at calving (P < 0.05 and P < 0.01, respectively). Both parameters showed no significant differences between the superficial and deep stromal layer, and they were significantly correlated with each other. A significant increase in the percentage denaturation of the deep stromal layer occurred between the second trimester and term pregnancy (P < 0.01), whereas at calving, the percentage denaturation had not significantly increased compared to term. The percentage of collagen denaturation of the superficial stromal layer did not significantly change with stage of gestation or at parturition. Our findings indicate that cervical ripening is a combination of increased collagen synthesis and increased percentage of collagen denaturation, whereas at calving, an increased digestion of the denatured collagen leads to increased collagen loss from the cervical connective tissue. The finding that cervical ripening mainly takes place in the deep stromal layer of the cervix emphasizes the importance of a detailed description of the tissue sampling sites for a proper interpretation of the results obtained from biochemical studies of the cervix.

The cow could be a suitable model for studies concerning functional changes of the cervix. However, as in many species, the bovine cervix becomes softer in texture during the follicular phase of the estrous cycle compared to the luteal phase. In the present study, we explored if changes in the collagen network take place that could be responsible for this phenomenon and if regional differences in water content, collagen content, and collagen degradation along the cross-sectional and longitudinal axes of the cervix were present. Two groups of nonpregnant animals with different progesterone status were studied. One group (n = 11) was under high progesterone influence, and the other group (n = 12) was under low progesterone influence. The water content was derived from the weight of the samples before and after lyophilization. The collagen content and the ratio of collagenous to noncollagenous proteins (hydroxyproline:proline ratio) were determined by performing amino acid analysis on hydrolyzed samples using high-performance liquid chromatography. Collagen denaturation was quantified with a colorimetric assay by determining the amount of hydroxyproline released from samples treated with alpha-chymotrypsine. The water content of the superficial layer of the submucosa was always significantly (P < 0.01) higher than the water content of the deep layer in the vaginal, mid, and uterine segments, but this was unrelated to the progesterone status of the animals. No effect of the tissue layers or of the progesterone status of the animals on the collagen content was observed, but an effect of segment was noted. The collagen content (mug/mg dry wt) in the vaginal segment of the cervix was significantly higher than in the mid (P < 0.05) and the uterine (P < 0.01) segments. The hydroxyproline:proline ratio showed the same pattern as the collagen content. The percentage of collagen denaturation in the superficial layer was always significantly (P < 0.01) higher than that in the deep layer, but no effect of the progesterone status or of the segment along the longitudinal axis was seen. It is concluded that regional differences in collagen biochemistry are present in the cervix of nonpregnant cows, which may account for the difference in firmness of different parts along the circular or the longitudinal axis of the cervix. However, differences in texture of the cervix between the two groups of cows could not be explained by differences in the collagen content, percentage of collagen denaturation, or water content.

The temporal relationship between changes in cervical dilatation, uterine electromyographic (EMG) activity, and maternal plasma concentrations of estradiol 17beta (E(2)), progesterone (P(4)), and 13,14-dihydro-15-keto-prostaglandin-F(2alpha) (PGFM), was investigated in six parturient cows. Calving was induced with a single injection of a synthetic analogue of prostaglandin F(2alpha) (PG) on Day 274 of gestation. Cervical dilatation was measured continuously by measuring the transit time between two implanted ultrasound crystals while at the same time uterine EMG activity was measured through two silver electrodes sutured on the myometrial surface until the expulsive stage of calving had been reached. In blood samples collected at 4-h intervals, starting at the moment of PG injection, the mean plasma E(2) concentration gradually increased and was significantly elevated at 28 h after PG injection. At 4 h after PG treatment, the mean P(4) concentration had dropped significantly and continued to decrease until a value of around 1 ng/ml was reached, where it stayed until the onset of expulsion. Mean plasma PGFM concentrations increased steadily after PG injection, reaching significantly elevated concentrations at 20 h after treatment. In the five cows that delivered calves in anterior positions, uterine EMG activity, expressed as root mean square (RMS in microV), started to increase at a mean interval (+/- SD) of 13.1 +/- 3.7 h following PG treatment. The increase in EMG activity was significantly correlated with changes in plasma PGFM concentrations. In these cows, dilatation of the caudal cervix started after a mean (+/- SD) interval of 28.5 +/- 1.5 h following PG treatment and dilatation progressed at a mean (+/- SD) rate of 2.25 +/- 0.24 cm/h. In one cow with a calf in the posterior position, uterine EMG activity and dilatation started at 15.8 h and 31.8 h, respectively, after induction of calving. We conclude that a predictable sequence of physiological changes occurs around induction of calving, which allows specific timing of future studies on cellular and biochemical changes within the cervix during parturition.

Preantral follicles (140-160 microm) were isolated mechanically from the ovaries of 10-day-old rats and cultured in groups of four to six for 6 days in medium containing 0, 1, 10, or 100 ng/ml of activin A. Activin stimulated (P < 0.05) the growth of preantral follicles in a dose-dependent fashion and enhanced the proliferation of preantral, oocyte-free follicular cells. Furthermore, treatment with activin induced the majority of follicles to form an antrum-like structure and helped to maintain the ultrastructure of these follicles during culture. Activin A also induced further changes characteristic of follicle and oocyte maturation, such as the elongation of granulosa cells contacting the oocyte and migration of the cortical granules to the oocyte cortex. In addition, gene expression for activin and activin receptor type II (ActR II) was demonstrated in both the oocytes and the somatic cells using the reverse transcription-polymerase chain reaction, and immunohistochemical studies demonstrated the presence of activin and ActR II proteins in the somatic tissue and, especially, the oocytes of these follicles. It is concluded that, in vitro, activin A stimulates the growth of rat preantral follicles and promotes antrum formation. Furthermore, because activin A and ActR II are synthesized within preantral follicles, intrafollicular activin likely plays an important role in early follicular development.

The temporal relationship among changes of the concentrations of the 13,14-dihydro-15-keto metabolite of prostaglandin F2 alpha (PGFM), estrone (E1) and estrone sulphate (E1S) in maternal arterial plasma (MP) and amniotic fluid (AF), the prepartum progesterone (P4) decline in MP, and the evolution of uterine electromyographic (EMG) activity was investigated in 6 cows. Calving was induced by a single i.m. injection of 5 mg flumethason on Day 270 of gestation. The period under investigation was subdivided into four consecutive periods: Period 1 covered the last 2 days before flumethason treatment; Period 2 (mean +/- SEM duration: 16.1 +/- 2.5 h), Period 3 (8.8 +/- 1.1 h), and Period 4 (13.0 +/- 1.5 h) together included the interval between injection and the onset of the expulsive stage of induced parturition. Each was defined by its pattern of uterine EMG activity. During Periods 1 and 2, this activity occurred in long episodes (2-20 min; contractures) at a similar mean (+/- SEM) frequency (0.51 +/- 0.14/h and 0.42 +/- 0.07/h, respectively). No significant differences in hormonal concentrations in MP and AF between these two periods were detected. During Period 3, contractures nearly disappeared (freq: 0.09 +/- 0.05/h), and in MP mean P4 levels were significantly lower and PGFM levels were significantly higher than before. Mean PGFM concentrations in AF were not significantly changed during Period 3. Finally, during Period 4, EMG activity reappeared and a parturient EMG pattern gradually evolved in the presence of a further significant decline of P4 levels and significant increase of PGFM concentrations in MP.(ABSTRACT TRUNCATED AT 250 WORDS)