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Early spring sex differences in luteinizing hormone response to gonadotropin releasing hormone in co-occurring resident and migrant dark-eyed juncos ( Junco hyemalis )

View Article: PubMed Central - PubMed

ABSTRACT

In early spring female juncos vary in LH following repeated stimulation with GnRH.

Resident and migrant males do not vary in LH.

Suggests the pituitary as a critical point of control for reproductive timing.

Sex difference suggests selection shaped responsiveness at critical time points.

Sex difference suggests selection shaped responsiveness at critical time points.

No MeSH data available.


Circulating LH levels in resident and migrant juncos: A) Males: Circulating LH levels in both residents and migrants were significantly elevated following a single as well as following three GnRH injections, compared with baseline (p < 0.05). Post-hoc pair-wise comparisons revealed no significant differences between resident and migrant male juncos at any of the three sampling time points, although resident males tended to have slightly elevated levels of LH at baseline and following a single GnRH injection. B) Females: Circulating LH levels in both residents and migrants were significantly elevated following a single as well as following three GnRH injections, compared with baseline (p < 0.05). Resident and migrant female LH levels did not differ at baseline, or following a single injection with GnRH. Resident females following three GnRH injections however displayed significantly elevated LH levels compared with migrant females. * indicate significant differences revealed by post-hoc analysis (p < 0.05).
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f0010: Circulating LH levels in resident and migrant juncos: A) Males: Circulating LH levels in both residents and migrants were significantly elevated following a single as well as following three GnRH injections, compared with baseline (p < 0.05). Post-hoc pair-wise comparisons revealed no significant differences between resident and migrant male juncos at any of the three sampling time points, although resident males tended to have slightly elevated levels of LH at baseline and following a single GnRH injection. B) Females: Circulating LH levels in both residents and migrants were significantly elevated following a single as well as following three GnRH injections, compared with baseline (p < 0.05). Resident and migrant female LH levels did not differ at baseline, or following a single injection with GnRH. Resident females following three GnRH injections however displayed significantly elevated LH levels compared with migrant females. * indicate significant differences revealed by post-hoc analysis (p < 0.05).

Mentions: A significant three-way interaction between resident/migrant status, sex, and blood sampling time was observed (F2,97.3 = 4.32, p = 0.016). All 66 pair-wise comparisons derived from the 3-way interaction are reported in the Supplemental Materials. We briefly highlight here pair-wise comparisons relevant to the hypotheses we have set out to test. Males: Post-hoc pair-wise comparisons revealed no differences in circulating LH levels between resident and migrant males at baseline sampling (p > 0.05), following a single GnRH injection (p > 0.05) or following repeated (3x) injection with GnRH (p > 0.05) (Fig.2A). Females: Interestingly, while residents and migrant female LH levels did not differ at baseline (p > 0.05) or following a single GnRH injection (p > 0.05), resident females displayed elevated levels of LH compared with migrant females following three GnRH injections (t = −3.28, df, 135.05, p = 0.044) (Fig.2B).


Early spring sex differences in luteinizing hormone response to gonadotropin releasing hormone in co-occurring resident and migrant dark-eyed juncos ( Junco hyemalis )
Circulating LH levels in resident and migrant juncos: A) Males: Circulating LH levels in both residents and migrants were significantly elevated following a single as well as following three GnRH injections, compared with baseline (p < 0.05). Post-hoc pair-wise comparisons revealed no significant differences between resident and migrant male juncos at any of the three sampling time points, although resident males tended to have slightly elevated levels of LH at baseline and following a single GnRH injection. B) Females: Circulating LH levels in both residents and migrants were significantly elevated following a single as well as following three GnRH injections, compared with baseline (p < 0.05). Resident and migrant female LH levels did not differ at baseline, or following a single injection with GnRH. Resident females following three GnRH injections however displayed significantly elevated LH levels compared with migrant females. * indicate significant differences revealed by post-hoc analysis (p < 0.05).
© Copyright Policy - CC BY
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5036536&req=5

f0010: Circulating LH levels in resident and migrant juncos: A) Males: Circulating LH levels in both residents and migrants were significantly elevated following a single as well as following three GnRH injections, compared with baseline (p < 0.05). Post-hoc pair-wise comparisons revealed no significant differences between resident and migrant male juncos at any of the three sampling time points, although resident males tended to have slightly elevated levels of LH at baseline and following a single GnRH injection. B) Females: Circulating LH levels in both residents and migrants were significantly elevated following a single as well as following three GnRH injections, compared with baseline (p < 0.05). Resident and migrant female LH levels did not differ at baseline, or following a single injection with GnRH. Resident females following three GnRH injections however displayed significantly elevated LH levels compared with migrant females. * indicate significant differences revealed by post-hoc analysis (p < 0.05).
Mentions: A significant three-way interaction between resident/migrant status, sex, and blood sampling time was observed (F2,97.3 = 4.32, p = 0.016). All 66 pair-wise comparisons derived from the 3-way interaction are reported in the Supplemental Materials. We briefly highlight here pair-wise comparisons relevant to the hypotheses we have set out to test. Males: Post-hoc pair-wise comparisons revealed no differences in circulating LH levels between resident and migrant males at baseline sampling (p > 0.05), following a single GnRH injection (p > 0.05) or following repeated (3x) injection with GnRH (p > 0.05) (Fig.2A). Females: Interestingly, while residents and migrant female LH levels did not differ at baseline (p > 0.05) or following a single GnRH injection (p > 0.05), resident females displayed elevated levels of LH compared with migrant females following three GnRH injections (t = −3.28, df, 135.05, p = 0.044) (Fig.2B).

View Article: PubMed Central - PubMed

ABSTRACT

In early spring female juncos vary in LH following repeated stimulation with GnRH.

Resident and migrant males do not vary in LH.

Suggests the pituitary as a critical point of control for reproductive timing.

Sex difference suggests selection shaped responsiveness at critical time points.

Sex difference suggests selection shaped responsiveness at critical time points.

No MeSH data available.