海南油茶主要形态和经济性状及聚类分析

对海南澄迈等6个主要油茶分布县10个乡镇油茶资源主要形态和经济性状进行调查测定,比较其与高州油茶和普通油茶的差异,并进行聚类分析。结果表明:海南油茶种质资源在形态、茶油脂肪酸组成等方面具有多样性,海南油茶树体、花、果实以及叶片均小于高州油茶;海南油茶鲜出子率在19.84%~36.21%之间,干出仁率在49.64%~64.22%之间,种仁含油率为44.56%~52.21%;海南油茶子油的不饱和脂肪酸为87.58%~89.68%,亚麻酸含量低,仅为普通油茶的0~88.7%,而饱和脂肪酸显著高于普通油茶。聚类分析表明海南油茶同高州油茶和普通油茶具有显著区别,除海南博鳌资源外,其他海南油茶被划分为一类。本研究为海南省油茶资源分类以及资源开发提供了参考资料。     

采后晾晒对油茶种仁油脂产量及组分的影响

油茶(Camellia oleifera)是我国大力推广的优质油料树种。本研究分别取花后150和170 d油茶果实,比较新鲜提取、自然晾晒及不同光质晾晒后种仁含油率及脂肪酸含量,旨在为合理采收处理提供科学依据。结果表明,晾晒能够显著提高花后150 d油茶种仁出油率,其中‘华鑫’种仁出油率的增加达5.35%。覆盖蓝色膜晾晒最有利于花后150 d的‘华硕’油茶油脂采后合成,种仁出油率高达52.42%。晾晒对花后170 d油茶种仁出油率影响不大。无论晾晒与否,脂肪酸成分不变,花后170 d较花后150 d油茶种仁中硬脂酸和油酸含量均有增加,但是品种间差异不显著。     

园林树木增湿降温生态功能评价方法

试验以吉林农业大学校园内的9种园林树木为研究对象,将树冠由外向内分为4个部位(分别记为表层A、外层B、中层C和内层D),分别测定各部位单位叶面积蒸腾降温量的变化规律,分析比较种内和种间不同部位单位叶面积增湿降温量的变化,以期探讨园林树木增湿降温生态功能评价的合理取样部位。结果表明:9种园林树木树冠各测定部位的单位叶面积增湿降温量均由树冠外围向树冠内部显著降低,树冠不同测定部位增湿降温量与平均值比较,种间SD和CV的变化大于种内。9个树种不同部位单位叶面积增湿量平均值为2.32 kg m-2d-1,降温量平均值为0.45℃。其中,表层A和外层B的增湿量较平均值分别提高了23.71%和10.77%,中层C和内层D分别较平均值下降了8.62%和26.46%;表层A和外层B的降温量较平均值分别提高了22.22%和11.11%,中层C和内层D分别较平均值下降了8.89%和26.67%;外层B和中层C平均增湿降温量为2.35 kg m-2d-1和0.46℃,与各测定部位平均值基本一致。9个树种各测定部位增湿降温量的偏离程度和和离散系数与平均值比较,外层B和中层C与各测定部位平均偏离程度接近,离散系数外层B最低。因此,在评价园林树木增湿降温生态功能时,提出用外层B或中层C偏向B点处的叶片作为取样部位更为合理。     

不同种源黄连木种子形态特征及脂肪油品质的差异性分析

对10个种源黄连木(Pistacia chinensis Bunge)种子的形态特征、果实含油率、籽油的理化性质和脂肪酸成分及其相对含量进行了测定分析.结果表明,不同种源黄连木种子的形态特征有显著差异(P<0.05),黄连木种子的千粒莺29.22～39.90 g,种子长度4.47～5.17 mm,种子宽度4.15～4.92 mm,长宽比为1.02～1.13.不同种源黄连木果实各部分的含油率均有极显著差异(P<0.01),果实、果肉和种仁的平均含油率分别为29.61%～38.61%、40.38%～64.54%和44.81%～55.97%,以江西彭泽、陕西商洛和云南石林种源的黄连木果实含油率较高.不同种源黄连木籽油的理化性质差异极显著(P<0.01),各种源黄连木籽油的折射率为1.469 6～1.475 1、碘值为748～924 g·kg-1、酸值为9.7～79.7 mg·g-1、水分含量为0.12%～1.40%.从黄连木籽油中共检测出棕榈油酸、油酸、亚油酸、亚麻酸、棕榈酸、硬脂酸和花生酸等7种脂肪酸成分,其中不饱和脂肪酸的总相对含量高达73.97%～87.41%.综合分析结果显示,江西彭泽的黄连木种子大而饱满且含油率高,可作为生物柴油油料资源的优良种源;云南石林、安徽滁州和陕西商洛的黄连木籽油的不饱和脂肪酸含量较高,可作为食用油原料资源的适合种源.     

76株薄壳山核桃实生单株的果实品质差异及综合评价

对南京地区种植的76株薄壳山核桃〔Carya illinoinensis(Wangenh.)K.Koch〕实生单株的8项果实性状和种仁中5种脂肪酸含量的差异以及各指标的相关性进行分析,并筛选出单项性状优良的单株;在此基础上,结合主成分分析结果,对供试76株单株的果实品质进行综合评价.结果显示:8项果实性状(包括坚果质量、种仁鲜质量、坚果壳厚度、坚果纵径、坚果横径、果形指数、出仁率和含油率)以及种仁中5种脂肪酸(包括棕榈酸、硬脂酸、油酸、亚油酸和亚麻酸)的含量均有较大变异,变异系数为663%~2899%,其中,出仁率的变异系数最小,亚麻酸含量的变异系数最大,8项果实性状的变异系数总体上小于5种脂肪酸含量的变异系数.部分果实性状间极显著或显著正相关,少数果实性状间极显著或显著负相关,而5种脂肪酸含量间均极显著正相关,但脂肪酸含量与果实性状间总体上无显著相关性.主成分分析结果表明:在8项果实性状中,与坚果大小有关的性状较为重要;而5种脂肪酸含量均同等重要.对果实性状和脂肪酸含量的主成分分析结果显示:第1主成分的决定指标包括含油率以及棕榈酸、硬脂酸、油酸、亚油酸和亚麻酸的含量,第2主成分的决定指标包括坚果质量、种仁鲜质量、坚果壳厚度和坚果横径,说明薄壳山核桃果实评价的首要指标为种仁中脂肪酸含量,其次为果实大小.在利用坚果质量、种仁鲜质量、坚果壳厚度、出仁率、含油率、果形指数、油酸含量和不饱和脂肪酸含量8个单项指标优选单株的基础上,结合主成分分析结果,71号单株的综合得分较高,其种仁鲜质量、含油率以及油酸和不饱和脂肪酸的含量均较高,可作为优良品种选育的首选候选单株.根据上述研究结果,建议在薄壳山核桃不同育种目标的优良品种选育工作中,将主成分分析法作为单项性状筛选法的有效补充方法.     

梅花"粉皮宫粉"花色色素的花青苷实质和花色的动态变化

特征颜色反应和紫外-可见光谱分析初步表明梅花"粉皮宫粉"的粉红色花色色素为花青素-3-糖苷.用分光光度法检测梅花"粉皮宫粉"不同花发育时期、在树冠不同着生部位花朵花瓣的相对花青苷含量,结果表明"粉皮宫粉" 的花色主要存在着花发育时期而导致的时间变化.花色在蕾期最浓艳,花瓣展开后便逐渐变淡;在整个花发育时期,同一朵花不同层次花瓣的颜色浓淡均为外层花瓣>中层花瓣>内层花瓣,且不同层次花瓣颜色的变化趋势几乎一致.虽然树冠下部单花的花色浓于上部的、树冠内层的浓于外层的,但花朵在树冠的着生部位导致的花色差异并不显著.花青苷除了导致"粉皮宫粉"的粉红花色外,还可能增强其花的抗寒性,为花的凌寒而开创造了条件.本文可为梅花的美学鉴赏、梅花红色花色的机理探索及其色素的分子结构鉴定提供参考.     

中国石蒜鳞茎中淀粉粒的分布特征

以中国石蒜为材料,用软件Motic Images Advanced 3.2测量了其鳞茎淀粉粒的形态特征,并统计了不同部位淀粉粒的数目和大小.结果表明:中国石蒜鳞茎的淀粉粒面积范围为10.095～1 993.649 μm2,且随着面积增大淀粉粒出现的频率表现为单峰分布.不同大小的中国石蒜鳞茎中大、小淀粉粒的比例没有显著差异.石蒜鳞茎的上部、中部、下部的大、小淀粉粒的比例无显著差异,但同一个部位的内层、中层、外层鳞片的大、小淀粉粒的比例差异极显著.鳞茎盘中的淀粉粒面积在10.095～296.035 μm2之间.中国石蒜所有的鳞叶均着生在鳞茎盘上,鳞叶间的营养物质运输需要通过鳞茎盘来转运.在鳞茎发育过程中,外层鳞叶的营养物质被消耗供中层鳞叶发育,以满足叶片生长和形态建成,中层鳞叶所积累的光合产物供内层鳞叶的生长发育.     

不同产地山桐子果实含油率及其理化指标变异分析

以13个产地居群的山桐子果实为材料,测定其全果含油率,并选取5个居群的果实分别测定果肉、种子含油率进行变异分析。结果表明:(1)13个居群间山桐子果实含油率差异显著,四川各居群山桐子果实含油率明显大于其他地区,各个居群内果实含油率差异明显,极端变异程度较大。(2)5个居群山桐子果肉含油率均大于种子含油率,而果肉含油率变异系数及相对极差均小于种子。(3)聚类分析结果显示,朝天等7个居群聚为一类,其果实含油率较高,变异系数较小,可以作为进一步良种选育的材料;海拔等地理因素对山桐子果实含油率均有一定影响,但程度不一。(4)5个居群山桐子果实油脂折光率均较高,而酸值均较低,表明山桐子油品质好,纯度较高,而且不同居群山桐子油碘值差异显著,反映其油脂不饱和程度差异明显。     

贵州五种野山茶种子氨基酸及脂肪酸成分含量的研究

采用高效液相色谱(HPLC)和氨基酸比值系数法,对贵州五种野山茶种子氨基酸和主要脂肪酸成分含量进行了研究。结果表明:(1)五种野山茶种子中均含有13种氨基酸,不同种类的氨基酸总量差异极显著,必需氨基酸和非必需氨基酸含量的差异显著(P0.01,P0.05),且第一限制性氨基酸含量不同;长柱红山茶(Camellia longistyla)和贵州红山茶(C.kweichouensis)的氨基酸总量及人体必需氨基酸含量分别为33.01、13.29和26.33、10.38 mg·g~(-1)。(2)不同种类种子的千粒重、含油率、含水率皆呈显著差异(P0.01,P0.05),种子含油率与不饱和脂肪酸含量显著正相关(R=0.556、P0.05),种子不饱和脂肪酸含量与棕榈酸、饱和脂肪酸含量极显著负相关(R=-0.791,P0.01;R=-0.776,P0.01),其中长柱红山茶和贵州红山茶种子的含油率和不饱和脂肪酸含量分别为43.93%、71.89%和43.91%、71.85%。(3)小黄花茶(C.luteoflora)、皱叶瘤果茶(C.rhytidophylla)、贵州红山茶、长柱红山茶、美丽红山茶(C.delicata)所含必需氨基酸与总氨基酸比值分别为44.9、43.3、39.0、40.9、33.8,必需氨基酸与非必需氨基酸比值分别为81.6、76.4、64.0、67.4、51.0,除了美丽红山茶的比值系数偏低外,其余4种均达到了WHO/FAO的理想蛋白质标准,种子蛋白质均具有较高的营养价值,其中长柱红山茶和贵州红山茶的种子含油脂质量等级指标接近我国现行茶油标准(GB11765—2003),可以作为重要的优质油茶种质资源加以开发利用。     

南方红豆杉响应不同传粉式样的结实表现

采用开花前雌株短枝套袋隔离传粉、花期人工授粉、风媒传粉 对照 及其传粉障碍等几种传粉式样 ,比较不同传粉 授粉 方式对南方红豆杉 Taxus chinensis var.mairei 结实的影响 ;在风媒传粉条件下 ,研究了南方红豆杉不同种植行向、树冠不同方位、上下内外不同层面的结实表现 .结果表明 :南方红豆杉存在孤雌生殖现象 ,平均单枝结实率为 2 8.7% ,与风媒传粉相比较 ,存在极显著差异 P<0 .0 1 ;人工授粉能显著提高结实率 P<0 .0 5 2 0 .7% ;2～ 3月份开花期 ,江汉平原盛行东北风 ,在风媒传粉条件下 ,东西向种植的南方红豆杉有更多的授粉机会 ,其结实情况极显著优于南北向种植的 P<0 .0 1 ;东西向种植的南方红豆杉树冠果实的空间分布 ,受传粉条件包括风向、冠层方位及距传粉源的距离、冠层内外上下层次等因素的影响 ,方位间的结实量按东南西北方位依次为 :2 30 .375粒、185 .6 2 5粒、12 8.813粒、10 5 .4 38粒 ,呈递减趋势 ,冠外层结实量普通高于冠内层 ,树冠东向下外层结实量最高 4 16 .75粒 ,北向下内层最低 2 2 .0 0粒 .     

VARIATION IN AVERAGE SEED SIZE AND FRUIT SEEDINESS IN A FRUIT CROP OF A GUANACASTE TREE (LEGUMINOSAE: ENTEROLOBIUM CYCLOCARPUM)

A detailed examination of the ordinary 1980 fruit crop of an ordinary large adult guanacaste tree (Enterolobium cyclocarpum) in Guanacaste Province, Costa Rica (1980) shows that for fruits with about 6-16 seeds (range, 1-18 seeds per fruit) there is about ***1 g dry weight fruit tissue per seed (seeds averaging about 820 m each). Fruits that have about 1-5 seeds on average have 1.5-3 times as much dry fruit tissue per seed as do the seed-rich fruits, and also contain seeds that weigh about 8% more on average than the seeds in the seed-rich fruits. The average seed weight per fruit was found to decrease slightly if all sizes of fruits are considered, but to remain essentially constant over the range of 7-16-seeded fruits. This category contained 78% of the fruits. These findings suggest that different parts of the seed crop may end up in different dispersers and dispersers with different preferences for fruit seediness and tolerances for seed size may remove different portions of the seed crop.     

The impact of consumption of fruit by vertebrate and invertebrate frugivores on the germination success of an Australian rainforest seed

Abstract The consumption of fruits by vertebrates and invertebrates can be both advantageous or detrimental to the survival of the seeds they contain. This study investigated the effect of fruit size and consumption of fruit pulp by rodents and beetles on the germination of the seeds of Acmena graveolens, a tropical rainforest canopy tree found in northern Australia. As fruit size increased, germination success and the amount of pulp remaining on the fruits was greater. When beetles were absent, germination success was highest when most of the pulp was removed by rodents, suggesting that they removed an inhibitor of germination. When beetles were present, germination success did not differ significantly across pulp categories, so beetles apparently enhanced germination in seeds with little pulp initially removed, possibly by further removal of fruit pulp. In this study, both rodents and beetles enhanced germination success of A. graveolens seeds by consumption of fruit pulp. Acting as facilitators of germination is a relatively unusual role for both these frugivores that are generally considered to act as seed predators or (in the case of rodents) dispersers.     

The effect of frugivory on postdispersal seed removal and germination in the pantropical forest tree Antiaris toxicaria Leschenault

The quality of seed treatment by frugivores has an effect on seed removal after dispersal, seed germination and tree recruitment. We provide information on postdispersal seed removal, germination and subsequent recruitment in tropical forest tree species Antiaris toxicaria in Ghana. We tested whether postdispersal seed removal and germination rates were differentially affected by the following seed treatments: seeds that were spat out by monkeys with all fruit pulp removed and spitting seeds with fruit pulp partially removed as observed in some birds and bats. We used seeds of intact ripened fruits as control. Frugivore seed treatment and distance from bole affected seed removal patterns, whereas intact seeds were significantly removed from all seed stations. The germination success was greater for seeds that were spat out by monkeys and poor for seeds with fruit pulp partially removed and intact fruits. More recruits were recorded at the edge of the adult A. toxicaria canopy radius. There was weak relationship (r² = 0.042) between the number of recruits and distance away from the adult tree. Results suggest that the subsequent recruitment in tropical forest tree species may be enhanced by some frugivore fruit‐handling behaviour where fruit pulp is removed from the seeds without destroying the seeds.     

辽东栎芽库统计:芽的命运

植物体是一个构件集合体,植物的枝系伸展可由芽库出生率、死亡率的统计学过程来分析。在东灵山地区,应用随机枝取样法调查了辽东栎芽的命运,并对其与枝长、叶数、果数等的关系进行了统计分析。结果表明：（1）辽东栎的芽或保持休眠状态,或死亡后脱落,或分化为营养枝、生殖枝（包括雄花枝、雄花序、雌花枝和两花枝）等;（2）不同生境中芽的命运不同,生活在林窗中的幼树上的芽分化为具有生殖功能的枝条的比例显著高于郁闭林中的幼树,而与成熟个体接近;（3）芽的命运还受其它因子的影响,如上层枝条上、或叶数多的长枝上的芽分化为生殖枝的可能性大于其它的芽,另外还发现结实枝的枝长、枝上叶数都明显高于非结实枝。     

Interactions between, Camellia japonica and its Seed Predator Curculio camelliae

Abstract Seeds of Camellia japonica are heavily attacked by Curculio camelliae. To evaluate the efficacy of fruit wall thickness against the curculio attack, correlations of fruit wall thickness with the ratio of seed survival (RSS) and with the ratio of oviposition success of the curculio beetles (ROS) were investigated on fruits collected at Camellia stands in Kinki District. While ROS exhibited negative correlations with the thickness of fruit wall in every stand, RSS showed different modes in accordance with the population density of the curculio. At low density, no significant difference was seen in RSS between trees with thicker fruit wall and those with thinner ones; the latter trees, generally bearing many fruits, had more seeds surviving than the former, generally bearing a few fruits. In high density curculio populations, RSS values showed correlation with the thickness of the fruit wall and more seeds survived in trees with thicker fruit walls. These facts suggest that two contrasting behavioral traits are present in a single species C. japonica and their efficacies differ in accordance with the curculio density.     

Do frugivorous birds concentrate their foraging activities on those alien plants with the most abundant and nutritious fruits in the South African Mediterranean-climate region?

Alien plants with abundant and nutritious fruits may compete more effectively for avian dispersal services than native shrubs. This premise was examined by comparing daily foraging activity (visitation frequency, foraging bird number and foraging period) by four frugivorous bird species of different size on fruits of two native and two alien shrub species co-occurring at four different sites. Also, the quantities of seeds consumed daily by each of the four birds species from fruits of the four shrub species were measured and compared with the numbers of fruits and seeds, and the mass of fruits present in the shrub canopies as well as with their fruit monosaccharide concentrations. The quantities of seed consumed daily by four different size bird species (Columba arquatrix, Colius striatus, Pycnonotus capensis, Zosterops pallidus subsp capensis) were positively correlated with the numbers of seeds per m² of canopy area and with fruit mass and fruit monosaccharide content per m² of canopy area, as well as with the monosaccharide concentration of individual fruits, except in the C. arquatrix (African olive pigeon). All four bird species displayed the highest daily visitation frequencies on fruits of the alien Solanum mauritianum which were more abundant and nutritious than fruits of the other alien Lantana camara and fruits the natives Olea europaea subsp africana and Chrysanthemoides monilifera. They also all consumed greater quantities of seed daily from fruits of the alien S. mauritianum than from fruits of the other shrub species. These results corroborate proposals that frugivorous birds concentrate their foraging activities on those alien plants with the most abundant and nutritious fruits.     

Fruit characters as a basis of fruit choice and seed dispersal in a tropical forest vertebrate community

Summary Interactions between a large community of vertebrate frugivore-granivores (including 7 species of large canopy birds, 19 species of rodents, 7 species of ruminants, and 6 species of monkeys), and 122 fruit species they consume, were studied for a year in a tropical rainforest in Gabon.The results show how morphological characters of fruits are involved in the choice and partitioning of the available fruit spectrum among consumer taxa. Despite an outstanding lack of specificity between fruit and consumer species, consideration of simple morphological traits of fruits reveals broad character syndromes associated with different consumer taxa. Competition between distantly related taxa that feed at the same height is far more important than has been previously supposed. The results also suggest how fruit characters could have evolved under consumer pressure as a result of consumer roles as dispersers or seed predators. Our analyses of dispersal syndromes show that fruit species partitioning occurs more between mammal taxa than between mammals and birds. There is thus a bird-monkey syndrome and a ruminant-rodent-elephant syndrome. The bird-monkey syndrome includes fruit species on which there is no pre-dispersal seed predation. These fruits (berries and drupes) are brightly colored, have a succulent pulp or arillate seeds, and no protective seed cover. The ruminant-rodent-elephant syndrome includes species for which there is pre-dispersal predation. These fruits (all drupes) are large, dull-colored, and have a dry fibrous flesh and well-protected seeds.     

Phenology of Tree Species in Bolivian Dry Forests

Phenological characteristics of 453 individuals representing 39 tree species were investigated in two dry forests of the Lomerío region, Department of Santa Cruz, Bolivia. The leaf, flower, and fruit production of canopy and sub–canopy forest tree species were recorded monthly over a two–year period. Most canopy species lost their leaves during the dry season, whereas nearly all sub–canopy species retained their leaves. Peak leaf fall for canopy trees coincided with the peak of the dry season in July and August. Flushing of new leaves was complete by November in the early rainy season. Flowering and fruiting were bimodal, with a major peak occurring at the end of the dry season (August–October) and a minor peak during the rainy season (January). Fruit development was sufficiently long in this forest that fruiting peaks actually tended to precede flowering peaks by one month. A scarcity of fruit was observed in May, corresponding to the end of the rainy season. With the exception of figs (Ficus), most species had fairly synchronous fruit production. Most canopy trees had small, wind dispersed seeds or fruits that matured during the latter part of the dry season, whereas many sub–canopy tree species produced larger animal– or gravity–dispersed fruits that matured during the peak of the rainy season. Most species produced fruit annually. Lomerio received less rainfall than other tropical dry forests in which phenological studies have been conducted, but rainfall can be plentiful during the dry season in association with the passage of Antarctic cold fronts. Still, phenological patterns in Bolivian dry forests appear to be similar to those of other Neotropical dry forests.     

濒危树种闽楠种子和幼苗生态学研究

从1995至1998年,通过种子收集器布设、不同程度圈围的样方处理、实验室和野外发芽实验、相邻格子样方调查和土壤中种子的筛选等一系列方法,对福建罗卜岩闽楠种子质资源保护区内闽楠为优势的常绿阔叶林群落中闽楠种群的果实、种子库、种子散布、果实／种子捕良、种子萌发和幼苗存活等进行了研究。结果表明：1995至1996年果实量为116个／m^2,成熟高峰期在1996年1月中旬。1997年至1998年为103个/m^2,成熟高峰期在1997年12月中旬。1997年至1998年,绝大部分（90．1％）的果实直接从母树上掉落,低于9．5％的果实由鸟类传播。实验室的种子发芽率为93％,而在野外仅为12％。野外发芽率低多由种子霉烂引起。闽楠的种子寿命较短,其种子在次年4月初开始萌发,7月之后地面种子即丧夫活力。动物捕食不仅影响种子的存活,同时也影响幼苗的死亡率,未经圈围与样地中被取食的果实和幼苗数量有显著差异。在新形成的林窗中或远离母树均降低了果实的迁移和幼苗的死亡率。但各因素交互作用有所不同。密度相关效应发生在2－3个月的幼苗阶段,之后,密度高低对果实被取食和幼苗死亡没有显著的影响。这些结果表明,闽楠种子和幼苗经历较大的环境压力,即在高湿度生境中母树树冠下的种子不仅易受到土壤病原菌的感染,同样容易遭受动物所捕食,从而导致较低的野外种子发芽率和幼苗存活率。这是闽楠致濒的重要原因之一。     

FRUIT TRAITS,AND SEED CONSUMPTION BY RODENTS,OF CRESCENTIA ALATA (BIGNONIACEAE) IN SANTA ROSA NATIONAL PARK,COSTA RICA

The pulp in the large hard fruits of Crescentia alata (Bignoniaceae: jicaro) are eaten by horses, surrogate Pleistocene dispersal agents, and the seeds pass through the horse to germinate in dung. I hypothesize that the distribution of jicaro has probably changed dramatically with the introduction of the horse. Two samples of ripe jicaro fruits weighed an average of 210 and 390 g, and contained an average of about 400 and 600 seeds. There was strong variation within and between two trees in the number of seeds per fruit. Mature live seeds weighed an average of 36 and 40 mg, but varied strongly in weight between and within fruits. The seeds were found to be highly edible to a small terrestrial native rodent (Liomys salvini, Heteromyidae) and this rodent avidly harvests the seeds from horse dung but cannot open the hard fruits by itself. The interaction between horses, jicaro fruits, and Liomys mice is probably representative of that which used to occur between Pleistocene megafauna and a number of contemporary Central American trees.