Emerging directions in the study of the ecology and evolution of plant-animal mutualistic networks: a review

The study of mutualistic plant and animal networks is an emerging field of ecological research. We reviewed progress in this field over the past 30 years. While earlier studies mostly focused on network structure, stability, and biodiversity maintenance, recent studies have investigated the conservation implications of mutualistic networks, specifically the influence of invasive species and how networks respond to habitat loss. Current research has also focused on evolutionary questions including phylogenetic signal in networks, impact of networks on the coevolution of interacting partners, and network influences on the evolution of interacting species. We outline some directions for future research, particularly the evolution of specialization in mutualistic networks, and provide concrete recommendations for environmental managers.

Dynamics of a Mutualistic Model with Diffusion

This article is concerned with a system of semilinear parabolic equations with no-flux boundary condition in a mutualistic ecological model. Stability result of the equilibrium about relevant ODE problem is proved by discussing its Jacobian matrix, we give two priori estimates and prove that the model is permanent when ε1 ＋ε2≠ 0. Moreover sufficient conditions for the global asymptotical stability of the unique positive equilibrium of the model are obtained. Nonexistence of nonconstant positive steady states of the model is also given. When ε1 ＋ε2 = 0, grow up property is derived if the geometric mean of the interaction coefficients is greater than I （a1a2 〉 1）, while if the geometric mean of the interaction coefficients is less than I （a1a2 〈 1）, there exists a global solution. Finally, numerical simulations are given.

BLOW-UP IN A FRACTIONAL LAPLACIAN MUTUALISTIC MODEL WITH NEUMANN BOUNDARY CONDITIONS

In this paper,a fractional Laplacian mutualistic system under Neumann boundary conditions is studied.Using the method of upper and lower solutions,it is proven that the solutions of the fractional Laplacian strong mutualistic model with Neumann boundary conditions will blow up when the intrinsic growth rates of species are large.

From Mutualistic Partner to Hunted Prey?

Sharks and sharksuckers maintain a mutualistic symbiotic relationship;thus, it is surprising to observe a lemon shark, Negaprion brevirostris, killing a sharksucker, Echeneis lucrates, which has been recorded during a dive with lemon sharks. Does this observation indicate that the symbiosis between the two species may shift occasionally? The awkwardness of the recorded kill, combined with its comparatively long duration, suggests this bout be a freak incident, rather than a common occurrence;thus, the mutualistic relationship needs not be questioned. What triggered the bout, however, can only be speculated. Although the caloric value of the killed sharksucker is not known, a feeding-oriented behavior can likely be rejected as the potential cause based on the teleost’s rather small size, and an irritation related issue is more likely to have triggered this bout.

反向散射通信技术的研究与发展

反向散射通信作为物联网部署的重要技术手段,其主要思想是利用入射信号进行低功耗被动通信和能量收集,以期实现物联网节点的能源自持。为了加深对该技术的认识并推动相关领域的发展,对现有研究展开综述并对未来发展进行展望。首先,阐述了反向散射通信的基本原理及架构演进。其次,针对不同的通信架构,对已有工作进行了综述。在此基础上,给出了融主被动传输的互惠共生反向散射通信架构,并进行了初步的研究和仿真分析。最后,结合已有研究探讨了所提通信架构的未来研究方向。

Coexistence in a mutualistic model with cross-diffusion in a heterogeneous environment

To understand the impact of environmental heterogeneity and mutualistic interaction of species, we consider a mutualistic model with cross-diffusion in a heterogeneous environ- ment. Semi-coexistence states have been studied by using the corresponding eigenvalue problems, and sufficient conditions for the existence and non-existence of coexistence states are given. Our results show that the model possesses at least one coexistence solution if the intrinsic populations growth rates are big or free-diffusion and cross-diffusion coefficients are weak. Otherwise, the model have no coexistence solution. The true solutions are obtained by utilizing the monotone iterative schemes. In order to illustrate our analytical results, some numerical simulations are given.

Asymptotic profile of a mutualistic model on a periodically evolving domain

In order to investigate the impact of periodically evolving domain on the mutualism interaction of two species,we study a mutualistic model on a periodically evolving domain.To overcome the difficulty caused by the advection and dilution terms,we transform the model to a reaction-difusion problem in a fixed domain.By means of eigenvalue problems,the threshold parameters are introduced.The asymptotic profiles of the solutions on an evolving domain are studied by using the threshold parameters and the upper and lower solutions method.The impact of the domain evolution rate on the persistence or extinction of species is analyzed.Numerical simulations are performed to illustrate our analytical results.

光照、磷和AMF对白车轴草生长的影响

外来植物成功入侵受非生物因素与生物因素的共同调控。本研究以典型入侵植物白车轴草(Trifolium repens L.)为研究对象,通过三因素两水平正交实验,探究光照(L)、磷(P)和丛枝菌根真菌(Arbuscular mycorrhizal fungi,AMF)及其交互作用对其生长的影响。结果显示:(1)高光照、高磷和接种AMF均显著提高白车轴草的生物量及生长速率,且接种AMF对生物量的促进作用随着光照的增加而增强,低磷条件下AMF对总生物量和相对生长速率的促进效应更明显;(2)高光照降低比叶面积;高磷和接种AMF显著增加叶片数和总叶面积,在高光强下尤为明显;(3)高光照可显著提高根表面积、根直径和根质量分数,但降低细根占比和比根长。高磷显著降低根质量分数。不接种AMF时,高磷增加根表面积与根直径,降低细根长占比;但接种AMF后,高磷则降低根表面积与根直径,增加细根长占比。AMF显著降低根质量分数和比根长。研究结果表明,三种因素对白车轴草的生长具有显著影响,且磷和AMF对其生长及地上性状的影响与光照强度相关,AMF对其地下性状的影响与磷浓度相关。

牛羊育肥与族际互动:农牧交错地带多民族共生互惠共同体的生成

牛羊育肥作为农牧结合地带的一种特色产业,不仅成为农牧民增收致富的重要渠道,而且串联起不同区域与环节过程中的各个民族,将之编织到同一个有机的经济社会网络之中,成为促进各民族交往交流交融的重要途径。青海循化的牛羊育肥产业在牛羊贩运、育肥、屠宰、出售等各个阶段中,撒拉族、藏族、回族、汉族等民族都存在着广泛且深入的交往交流,并在这一过程中形成了跨区域跨民族的互惠互助关系。牛羊育肥所推动形成的多民族共生互惠关系,为构建和谐的民族关系树立了典型案例,对当前推进各民族交往交流交融具有重要启示意义。

Internal Stabilization of a Mutualistic Reaction Diffusion System

We study the internal stabilization of steady-state solutions to a 2-species mutualistic reaction diffusion system via finite-dimensional feedback controllers. Our main idea is to use different internal controllers to stabilize different steady-state solutions. The controllers axe provided by considering LQ problems associated with the lineaxized systems at steady-state solutions.

Positive Steady States of a Competitor-Competitor-Mutualist Model

In this paper we deal with the positive steady states of a Competitor-Competitor-Mutualist modelwith diffusion and homogeneous Dirichlet boundary conditions.We first give the necessary conditions,and thenestablish the sufficient conditions for the existence of positive steady states.

The spreading fronts in a mutualistic model with delay

This paper is concerned with a system of semilinear parabolic equations with two free boundaries describing the spreading fronts of the invasive species in a mutualistic eco- logical model. The local existence and uniqueness of a classical solution are obtained and the asymptotic behavior of the free boundary problem is studied. Our results indi- cate that two free boundaries tend monotonically to finite or infinite limits at the same time, and the free boundary problem admits a global slow solution with unbounded free boundaries if the intra-specific competitions are strong, while if the intra-specific competitions are weak, there exist the blowup solution and global fast solution.

GLOBAL ATTRACTIVITY IN AN ALMOST PERIODIC PREDATOR-PREY-MUTUALIST SYSTEM

In this paper, the almost periodic predator-prey-mutualist model with Holling type II functional response is discussed. A set of sufficient condi- tions which guarantee the uniform persistence and the global attractivity of the system are obtained. For the almost periodic case, by constructing a suit- able Lyapunov function, sufficient conditions which guarantee the existence of a unique globally attractive positive almost periodic solution of the system are obtained. An example together with its numerical simulations shows the feasibility of the main results.

一类含扩散时滞的生态模型的周期解存在与稳定性

研究一类Competitor-Competitor-Mutualist生态模型,通过特征值问题来构造系统的上下解,利用比较原理证明在一定条件下该模型的零平衡态及半平凡周期解的全局稳定性,并获得了这个系统具有一对周期拟解的充分条件,且对任意的非负初值函数这对周期拟解构成的区间是此系统的一个吸引子.

“螺-草”的互利关系

水生态系统中存在螺-草互利现象。然而,植食性螺类与水生植物之间是否存在这种互利关系目前尚无定论。椭圆萝卜螺(肺螺亚纲)与铜锈环棱螺(前腮亚纲)是常见的淡水螺类,其中,椭圆萝卜螺能牧食多种水生植物的活体。通过室外实验,研究了这两种螺类在不同密度条件下对沉水植物(苦草)生长的影响。实验结果表明,低密度的椭圆萝卜螺促进了苦草的生长,螺、草之间存在明显的互利关系,高密度时螺类对苦草植株本身的大量牧食则显著限制了植物的生长。对铜锈环棱螺而言,不同密度的螺类均明显促进了受附生生物胁迫的苦草的生长,螺-草互利关系成立。分析认为,螺-草互利关系的存在是有其限制条件的,对植食性螺类而言,只有在较低的螺类密度条件下才存在这种互利关系。

印度梨形孢的生物学效应及其作用机制

印度梨形孢(Piriformospora indica)是最近发现的一种植物根部内生真菌.本文简要综述了印度梨形孢的生物学性状、与植物的互作以及在促进植物生长发育、提高抗病抗逆能力的作用及其机制.

松材线虫与其携带细菌之间的相互影响

笔者研究了从松材线虫体上分离的2 株强致病菌和1 株弱致病菌与松材线虫的相互影响。结果表明:强致病菌荧光假单胞菌(Pseudomonas fluorescens) GcM5 1A菌株、恶臭假单胞菌(Pseudomonas putida)ZpB1 2A菌株能够明显地促进无菌松材线虫的产卵量增加、繁殖速度加快和成虫虫体生长;同时,松材线虫也能促进强致病菌荧光假单胞菌GcM5 1A菌株、恶臭假单胞菌ZpB1 2A菌株的繁殖。而泛菌(Pantoea sp.)ZM2C菌株完全抑制了无菌松材线虫的繁殖,无菌松材线虫对泛菌ZM2C菌株的繁殖亦具有显著抑制作用。由此说明松材线虫与其携带的某些致病菌之间存在互惠共生现象,松材线虫携带的致病菌并不是偶然的污染,它们之间的互惠共生现象是在长期共生进化中形成的。笔者还讨论了互惠共生现象在松材线虫致病过程中的作用。

西双版纳榕树及其隐头果内的小蜂群落

榕属的4个亚属在西双版纳均有分布,目前已报道榕树69种、亚种和变种,占全国已报道榕树种类的69.4%,其中榕亚属23个种和变种:白肉榕亚属4个种:聚果榕亚属2种和变种;无花果亚属41个种、变种和亚种。在榕树隐头果内生活着种类专一的传粉榕小蜂和一些非传粉小蜂。西双版纳地区目前已分类鉴定29种榕树的30种传粉小蜂和170多种非传粉小蜂,其它榕树种类及其隐头果内的小蜂种类还未获得活体标本而没有确切的分类定名。传粉小蜂与非传粉小蜂以及各种非传粉小蜂之间相互影响,并影响着榕树与传粉小蜂形成的共生体系,它们共同构成了榕树隐头果内复杂的小蜂群落。对榕树隐头果内小蜂群落的研究目前还处于初级阶段,主要都集中在传粉小蜂的研究上,非传粉小蜂的研究国内外都较少,且对于各种小蜂之间的关系以及它们与榕树之间的关系,还需更深入、具体的生态学、生物学、遗传学、分子生物学等各方面的综合研究。

粗叶榕(Ficushirta)繁殖系统的特征及其共生的榕小蜂

本文对粗叶榕(FicushirtaVahl)的外部形态、花序结构以及寄主和传粉者的繁殖特性作了比较详细的观察和研究,讨论了它们互惠共生关系的一些基本特征。它的专性传粉者是榕小蜂科(Agaonidae)榕小蜂亚科(Agaoninae)的爪哇榕小蜂(BlastophagajavanaMayr)。观察发现粗叶榕还存在两种非授粉小蜂Sycoscaptersp.和Philotrypesissp.,它们在榕果外产卵。

杜仲愈伤组织超低温保存的研究

采用单因子比较、正交设计和均匀设计法，分别考察影响杜仲愈伤组织诱导、生长及其超低温保存的因素。试验表明：Ｂ５＋ＮＡＡ０．５ｍｇ／Ｌ＋６—ＢＡ１ｍｇ／Ｌ有利于意伤组织诱导。ＭＳ＋２．４—Ｄ３ｍｇ／Ｌ＋６—ＢＡ０．５ｍｇ／Ｌ则有利于愈伤组织快速生长。超低温保存的最佳材料是２周龄的愈伤组织。愈伤组织超低温保存的较好冷冻保护剂是１２．５％Ｇｌｙ＋７．５％ＰＥＧ＋２．５ｇ／ＬＬＨ。