Thermal conditions alter the mating behavior of males in a polygynous system

Males in polygynous systems may be facing a tradeoff between the traits that enhance reproductive success and the need to cope with environmental change. To secure mates, males invest into large bodies, lavish ornaments, and costly activities, but these investments may be incompatible with future environments. As climatic change intensifies, thermal stressors could be disrupting the energy-intensive pathways that historically have yielded mating opportunity.
We evaluated how traits associated with social dominance interacted with environmental conditions to shape mating behavior and opportunity in moose (Alces alces), a heat-sensitive species in which southern populations live at the edge of their thermal tolerance. We anticipated that males with favorable characteristics (e.g., age, weaponry) would allocate more to reproduction, resulting in increased mating opportunity. We expected that warm temperatures would limit reproductive effort, especially as age and weapon size increased.
We ..., Animal Capture and Handling
We chemically immobilized male and female adult moose (≥1 year) via helicopter (Levine et al. 2022). For the duration of the study, we sought to maintain 15 collared animals of each sex (approximately 30% of the population). We determined age via cementum annuli (Matson’s Laboratory, Milltown, MT) using the right, incisiform canine (Swift et al., 2002). We fitted all moose with GPS collars (VERTEX PLUS; Vectronic Aerospace GmBH). All GPS collars had hourly fix rates and three orthogonal accelerometers collecting 5-min averaged activity data. In autumns of 2020 to 2022, we classified antler size of GPS-collared male moose through field observation and photography.
Movement Metrics
To quantify mating tactics (mate-searching and female-defense), we identified likely behaviors with a three-state hidden Markov model (momentuHMM package) parameterized with the step length and turn angle of movement. Our model classified hourly GPS locations as either encamped, tort..., , # Thermal conditions alter the mating behavior of males in a polygynous system

[https://doi.org/10.5061/dryad.7sqv9s52b](https://doi.org/10.5061/dryad.7sqv9s52b)

## Description of the data and file structure

Movement metrics and individual data for moose in northwestern Wyoming during the mating season (2020-2022).

### Files and variables

#### File: FE-2024-00544\_Ages.txt

**Description:** Animal ages in years.

##### Variables

* AID: Unique ID for each animal.
* \"CaptYr: Year of tooth extraction.
* Age: Age in years of tooth when extracted.

#### File: FE-2024-00544\_AntlerScore.txt

**Description:** Animal antler scores.

##### Variables

* AID: Unique ID for each animal.
* FallYear: Year of antler growth.
* Score: Score of antler (1-5).

#### File: FE-2024-00544\_Activity.txt

**Description:** Activity data.

##### Variables

* AID: Unique ID for each animal.
* DateMST: Date and time of collection.
* axD: Accelerometer value, X-axis.
* ayD: Accelerometer value, Y-axis.
* azD: ...

在一雄多雌婚配系统（polygynous system）中，雄性个体往往面临着权衡取舍：一方面是提升繁殖成功率的性状投入，另一方面是应对环境变化的生存需求。为了获取交配机会，雄性会投入于更大的体型、华丽的装饰结构以及高成本的行为活动，但这类投资可能与未来的环境条件不相适配。随着气候变化加剧，热应激因子可能会破坏那些历来能带来交配优势的能量密集型生理通路。

本研究以驼鹿（Alces alces）这一热敏性物种为研究对象，其南部种群恰好处于热耐受极限的边缘。我们探究了与社会支配地位相关的性状如何与环境条件相互作用，进而塑造雄性的交配行为与交配机会。我们推测，具备有利性状（如年龄、角的发育程度）的雄性会将更多资源投入繁殖活动，从而获得更多交配机会；同时我们预期，高温会限制雄性的繁殖投入，且这一限制效应会随着雄性年龄与角尺寸的增大而愈发显著。

### 动物捕获与处理
我们通过直升机化学保定成年雌雄驼鹿（≥1龄）（Levine等，2022）。本研究全程力求维持每个性别各15只佩戴项圈的个体（约占种群总数的30%）。我们通过右侧门齿齿骨质年轮（Matson实验室，美国蒙大拿州米尔顿）来确定个体年龄（Swift等，2002）。为所有驼鹿佩戴GPS项圈（VERTEX PLUS；Vectronic Aerospace GmbH）。所有GPS项圈均设置为每小时定位一次，并搭载三个正交加速度计（accelerometer），以采集5分钟平均后的活动数据。在2020至2022年的秋季，我们通过野外观察与摄影对佩戴GPS项圈的雄性驼鹿的角尺寸进行分级。

### 运动指标
为量化交配策略（配偶搜寻与雌性守卫），我们基于移动步长与转向角参数化构建了三态隐马尔可夫模型（hidden Markov model，momentuHMM工具包），以此识别驼鹿的典型行为。我们的模型将每小时获取的GPS定位点划分为驻留、迂回…… # 热环境改变一雄多雌系统中雄性的交配行为

[https://doi.org/10.5061/dryad.7sqv9s52b](https://doi.org/10.5061/dryad.7sqv9s52b)

## 数据与文件结构说明
本数据集包含美国怀俄明州西北部驼鹿在繁殖季（2020-2022年）的运动指标与个体相关数据。

### 文件与变量说明
#### 文件：FE-2024-00544_Ages.txt
**文件说明：** 各动物的年龄（单位：年）。
##### 变量说明
* AID：每只动物的唯一标识符。
* CaptYr：牙齿采样年份。
* Age：采样时牙齿对应的个体年龄（单位：年）。

#### 文件：FE-2024-00544_AntlerScore.txt
**文件说明：** 各动物的鹿角评分数据。
##### 变量说明
* AID：每只动物的唯一标识符。
* FallYear：鹿角生长年份。
* Score：鹿角评分（1-5分）。

#### 文件：FE-2024-00544_Activity.txt
**文件说明：** 活动监测数据。
##### 变量说明
* AID：每只动物的唯一标识符。
* DateMST：数据采集的山地标准时间日期与时刻。
* axD：X轴加速度计读数。
* ayD：Y轴加速度计读数。
* azD：……